Quiet at nominal 1200 CFM (that is, a residential blower rated at 1200 CFM operated at full power) can be achieved by using a roof blower and in-line silencer, or in-line blower with in-line silencer. These configurations will, as far as I know, preclude the VaH designs.

An insert does not require any particular exterior welding beauty, except at the bottom where lights, light control, and fan control are placed. Is your plan for hood intake aperture size accounting for cooking plume expansion from all burners?

It is best to start with requirements and then filter available components to those contributing to required performance/cost/aesthetics compliance.

In some views, only the price of air is reasonable; necessary may be a better criterion.

I would avoid VAH. They are quite loud.

Probably more info than you want but you may find something useful here: https://www.gardenweb.com/discussions/5161173/hood-faq

I think it really depends. Nothing that moves that much air is going to be quiet.

If you can have remote blowers and inline mufflers, then you can reduce some of the sound; and in that case, a VAH might very well the obviously inferior choice. But even then, you still have the noise at the baffles. So, don't expect the hood to be whisper quiet.

We have a 20 odd year old VAH. As long as the vent pipe is adequately sized, it works great and noise level is IMHO in the expected range. We also have a new ModernAire hood with internal blowers. It has more power than our old VAH, but it can be really really loud. And part of that is simply the whistling sound that the air makes when it passes the baffles at full air velocity. If I turn down fan speed, it's about as loud as the old VAH.

In other words, I don't really perceive a big difference between either designs. Pick what works best considering all your other design constraints. And absolutely make sure that your vent pipe is as large as you can make it.

Interesting. My Wolf (Independent) hood's baffles only hiss at high air flow rates. One may surmise that there is a difference in baffle shape aerodynamics between the brands. Or, perhaps, the whistling sound is an interaction between the baffle exit air flow dynamics and the blower fan blades. My blower is on the roof so any such effect is not present.

If you find my post from 11 Oct 2018 in this thread: https://www.gardenweb.com/discussions/5161173/hood-faq

There is some discussion of noise levels.

It's important to keep in mind that adequate capture area (aperture) and containment area will allow for much lower CFM's and less noise for the same or better performance. This is why commercial hoods can be much quieter than residential. FWIW we are getting a commercial hood for our kitchen partially for better performance (I really dislike the odors of meals past) but also because it will be quieter.

A 1200 CFM hood does not have to run at 1200 CFM all of the time. 600 CFM may be adequate for 95% of cooking and so the full and louder force necessary only 5% of the time. When it's needed though it's nice to have it.

True. 90 ft/min across the entry aperture is only needed for the hottest cooking plumes. Lower levels should be fine. The lower limit, however, is determined by the point where centrifugal ejection of grease particulates at the baffles is inadequate, and when duct velocity is so low that condensation of grease occurs in the duct. These effects may result from such cooking as simmering bacon, where the grease content of the plume is high, but the temperature is low. Capture and containment are achieved, but the grease is not dealt with in a desirable manner. Half blower power might be a nominal minimum for low temperature high grease plumes.

As I wrote in one of opaone’s other threads, we‘ve had a Vent A Hood for 3 1/2 years. We do a lot of cooking on our Thermador rangetop. The hood does a great job of clearing the air of cooking odors, grease and gas. And, it’s ever so quiet. No problem carrying on a conversation, or watching TV while it’s on. We had the exhaust mounted in the attic, which is what keeps the sound level low.

Also, contrary to what opaone said in her previous post, we find the baffles in the hood easy to clean.

I have a 54" zephyr 1200 cfm hood insert - it is behind stone, over a 48" Bluestar. It is not quiet on full blast (6 levels) but no 1200 cfm is when it is 2 feet from your head. Only remote can achieve that. The lower levels (1-3 say) however, pretty much cover everything outside wok and red meat searing, are reasonably quiet and highly functional. Pretty easy clean too, baffles go in the dishwasher.