My info may be dated, but might still give you a useful perspective. Back in 1991 we installed a Broan that was appropriate for us at that time. It has just 250 cfm capacity, and a variable speed switch. The motor is installed in the attic just within the hole through which the exhaust is expelled. Remote location does cut down on noise, But there is a fair amount of air noise at top speed, the sound of rushing of air, because there are 2 relatively small air intakes in the range hood. The new rangemasters I've considered lately have air intakes that cover the whole undersurface of the rangehood. I think that's a big improvement. It will help to capture exhaust more effectively, and should cut down on air noise as well.

We have thought about upgrading our system with one of the new rangemaster units, to match the cfm exhaust requirements of our new gas range. But we're a retired couple and we rarely cook for more people than ourselves. So we're in no big hurry to make the change.

I think CR is useful for many things, but for something as complex as a kitchen exhaust system with very demanding requirements and installation requirements, it's impossible for them to provide more than general guidance.

If your space and budget permit, you should consider a hood that's a little bit wider than the width of your cooking surface and, in any case, should have a depth that reaches to about half of the front burners. With such high cfm capacities (which you need if your burners get hot enought to smelt iron ore !!), you should also consider the possibility of installing make-up air capability. I would recommend designing it so that such a system can be installed later if/when you decide you definitely need it. And, if you live in a frigid climate, you might need a means to heat the make-up air.

I hope this info is helpful.