If your stove is against an outside wall or can be vented through the attic/roof, pass on th e"downdraft".

Very deep? As in there is an 18” deep cabinet behind the range? Because that is what you physically need. And then, it will still be terrible ventilation that leaves your kitchen with grease and steam all over it.

Overhead venting is far superior.

Where is your range? We need to see the space. Downdrafts suck and not in a good way.

A downdraft will only exhaust about 5% of effluent with the rest spreading throughout your kitchen and house so is essentially worthless.

If a gas range then definitely do NOT use a downdraft but a properly sized and installed overhead hood.

If induction then the poor performance of a downdraft will not be a significant health risk but know that odors, grease and steam will spread throughout your house.

More: https://www.gardenweb.com/discussions/5161173/hood-faq