With conventional hood systems, the expectation is that the larger particles within the entire grease particle spectrum are collected by the baffles, and the smaller particles are ejected into the outside air, with only modest condensation or impact collection by the duct. To deal with the entire particle spectrum with a filter pack is a challenge, and probably unaffordable in cost for most residential users. If the Amazon rating is based on comparison to outside venting, the result above might be reasonable. As a commercial example, the Wells WVU-31CT filter system is described below: "Filtration Completely self-contained filtration process reduces emissions below that allowed in NFPA 96 and ANSI UL710B using the EPA 202 test method and includes stainless steel grease baffle filter with grease cup, fiberglass pre-filters, high-efficiency (Particulate Air) filter/ carbon-charcoal filter pack. All filters are easily removable with out tools. Air flow sensors continually monitor air flow optimizing performance and grease removal while an interlock system will not allow cooking appliances to function if filters are missing, clogged or in the event of a fire." About $18k. Electric surfaces only.

>How effective would a ductless/recirculating chimney style hood be? Far less effective than one that is vented, for sure. However, there are a number of hoods that can be set up to be recirculating--what style do you want? Stainless, stainless+glass, wood?

How tall are your ceilings? A mantle hood needs to have some height and width to be proportionate as a "mantle", and often that's incompatible with a smaller scaled room. One idea is to not take it to the ceiling. Use the area at the top to install a grate to expel the air. Or, run a duct inside the wall to an adjacent room, or through the ceiling joists to a grate in the room. Or run a duct through the top shelf of the cabinets to an end cabinet with a grate. A lot depends on the actual layout and construction details of the room.

Assuming a cooktop with a cooking area (contour around the union of hot pan base areas) of some dimensions L x D, a hood entrance aperture of dimension L + 6 x D + 6 (inches) would (in still air) provide sufficient capture up to about 36 inches of height over the cooktop. If there are strong cross drafts, then a larger aperture is recommended. Blower airflow (actual) capability should be of the order of 90 CFM/sq. ft. of hood aperture. If roof penetration and wall penetration are both out of the question, then adapting the methods of apartment type recirculating hoods may work, if not prohibited by the safety statement associated with the range. Such hoods need adequate layers of grease capture filters, and charcoal filters. Vent-a-hood and Broan/Best/NuTone may have units suitable for modest air flow requirements; for higher power cooking requirements, their approach would have to be adapted into a larger, more powerful unit. Perhaps custom hood fabricators such as ModernAire could rise to the occasion. A simple web search for a commercial counterpart led to this as one example of perhaps others: captiveaire.com This particular unit is too low in CFM for a cooktop. And because it is made of 430 stainless steel, in salt air it may need a dilute phosphoric acid wash now and then to brighten it up. See also http://ul.com/wp-content/uploads/2014/04/ul_RecirculatingHoodSystems.pdf and http://restaurantexhaustfans.com/how-effective-are-ductless-commercial-hoods/ And here is a snarky, albeit imperfect tract, part of which addresses this subject. The comments about cooking effluent constituents is pertinent: http://www.treehugger.com/kitchen-design/most-screwed-badly-designed-inappropriately-used-appliance-your-home-kitchen-exhaust.html (Please note that a hood cannot "suck" more than it "blows.") Anyway, the important point that I didn't elaborate upon in my first message is that when the hood exhaust air is directed to go "sailing out" along the ceiling, its velocity rapidly drops as the moving exhaust effluent's momentum interacts with the friction induced by the room air inertia. To succeed in the original plan without ducting would require a very powerful and loud "screaming-mimi" fan to accelerate the effluent such that much of it made it to whatever door was open. There would still be significant undesirable mixing with the room air. Some improvement might be achieved by also accelerating a cylinder of the same velocity clean air surrounding the effluent. I believe that achieving even partial success this way is much less practical than any duct scheme, including one that has to penetrate concrete. kas