To answer your question...in general, if you ... (1) have only one or two turns in your run to the outside (2) have the correct duct size (at least 8") (3) install it properly (usually no more than 30" off the cooking surface) (4) don't do a lot of frying or stir-frying and don't grill indoors (5) are installing against a wall (i.e., not an island or peninsula) ...then a vent around 600cfm is usually sufficient. However, if you... (1) grill indoors or do a lot of frying or stir-frying (2) have more than two turns (3) have a long duct run (4) are installing over an island or peninsula (5) want to install it higher than 30" off the cooking surface ...than higher cfms are needed. Additionally, if you get a hood w/higher cfms, then you can run it on a lower speed and it will be quieter. Note: Do not go with a duct less than 8" in diameter or a rectangular duct less than 50 sq inches. Smaller size ducting will not only be less effective, but louder. As to just opening a window instead...that will not properly vent, no matter what anyone tells you. To have a window be effective, you need all of the following all the time... First, you need a cross breeze that's going in the right direction; Second, your range/cooktop would need to be in front of the window so you're not sending the grease/smoke/etc. across the room first (defeats the purpose if it has to cross the room!); Third, you will need to be able to have the weather appropriate for year-round window opening...neither too hot nor too cold; and Fourth, you need to have a constant, fairly strong breeze to produce the airflow. For those that say you don't need a hood, I wish I could take you to my parents' home where there is a gunky build-up of grease/dust/smoke on the ceiling, walls, and surrounding cabinetry...they've never had a hood...and it shows despite periodic cleaning/wiping down! Here is a link that might be useful: Appliances Forum FAQ: Overview of vent hoods

I am the resident expert only because real HVAC systems engineers don't frequent this forum, as far as I know. Noise introduced into the kitchen will be significantly reduced if an external blower with silencer can be fitted. A lot of the high frequency blade tip turbulence caused noise will be removed. This is also true of an in-line (duct mounted) blower. The issue of the neighbor is difficult to assess. What is the configuration of his or her windows relative to your potential external blower (1500 CFM I assume you meant). Your own window sound transmission is also an unknown. Generally, the external noise could be abated by (a) using a silencer on each side of a duct mounted in-line blower, or (b), using a deliberately under-driven* "up-blast" commercial blower (mounted as a side blast). (I think opaone is using an under-driven blower for his new system.) It is also possible to use a chase to move the blower up to roof level. I have a 1500 CFM nominal Wolf (Broan) blower on my roof. Its sound level is detectable but not obtrusive from the ground, but it might be if in a wall location where the sound is "trapped" between two houses. Possibly a more expensive but similar in design Abbaka downslope unit would be marginally quieter. ------ * commercial blowers of this type can use a pulley system between motor and fan that allows for different ratios. By choosing a ratio that operates the fan blades below their rated speed when the motor is receiving maximum voltage, significant turbulence noise can be avoided. The physical cost is a larger unit than would otherwise be required for the desired flow rate. Residential blower fans are directly coupled to their motors.

Broan/NuTone/Best make a large range of ventilation equipments and generally you get what you pay for as far as I can tell. However, why a "high end" appliance dealer wouldn't include some other brands is unclear. At a minimum, I would expect a Wolf dealer to have examples of Wolf hoods. (My hood is a Wolf, made by Independent before Wolf moved production in-house.) Decide how high you want the hood for good site lines and reaching to the back burners, and missing one's head, while keeping in mind that the front burners will be emitting plumes that expand as they rise, so height corresponds to increases in needed overlap -- side to side and front to back. 10 degrees from vertical measured from the flame diameters when pans are on the burners can be used for plume expansion estimation. Sketch it out. Given a height and hence width and depth, calculate the square footage of the entry aperture of the hood. For wall hoods the light bar in the front may qualify as partial or whole entry aperture area. Multiply area by 90 CFM/sq. ft. Multiply by 1.5 if you don't know all the pressure losses. Find a blower that has that result as a rated value. Decide on in-hood, in attic (in line), or on roof. Farther away is generally quieter. If there is room for a silencer (Fantech) between blower and hood then the result will be quieter still. There is a lot of dissension about ease of hood cleaning by type. I can say that my Wolf hood baffle assemblies easily remove and can be cleaned in a dishwasher. (I have ten of these, so it takes two loads.) One still wants to reach up inside and wipe the surfaces. I use Simple Green, but likely there are myriad possible choices. I have never owned a VaH, and was initially repulsed (2007) by the Magic Lung® claims. Others like them. If you have guests sitting where they can see into the hood, a baffle system may be aesthetically superior. Duct should be sized so that full power actual flow rate achieves a velocity in the duct between 1000 and 2000 ft/min for best balance between grease condensation and grease impingement. You can go lower (larger duct) if you pre-heat the duct in cold weather. On CFM focus. Standard (if that actually ever applies) residential hoods are designed to fit into residential kitchens. Commercial hoods are designed to fit into commercial kitchens. At a minimum, the typical difference is two feet of ceiling height. When the commercial hood can be built so that there is tremendous volume below its baffles, there are conditions where the specific flow rate (CFM/sq. ft.) can be reduced below the value I suggested above. This is due to "baffle averaging" resulting from the reservoir volume vs. plume steady state and transient volumetric rates. At the other extreme, residential hoods with little volume below the baffles will allow plume escape (capture failure) if the plumes are not immediately entrained into the baffle flow. And, of course, plumes not initially captured are not contained and removed except as a matter of long term kitchen (and whole house) air replacement. So CFM focus varies. Another difference is that commercial hoods are typically operated at a fixed CFM and the MUA is balanced for this case, whereas residential hoods, along with bathroom fans, etc., operate at variable CFM, and this makes the MUA control more complex.

A local restaurant supply has contacts to a metalworker who can create something utilitarian and custom in stainless for a couple of thousand, not including the insert. If you are wanting something more aesthetic than utilitarian, that will not be a good option. The price goes up for that. A local metal sculptor artist type person is where to start that search. It may easily be that 15K or more though. Bluestar or Ventahood are both good options for many customizable options. If you are doing a 54” hood over a 48“ range, you are going to end up at a high price to a really high price, no matter what route you go, if you are choosing effective ventilation. That is because of all of the extra costs that are code required with large ranges. Backdrafting carbon monoxide is no joke, and it is why make up air is a code rquirement.