I am doing exactly the same thing. I am anxious to see what comments you receive.

I do not know of an induction cooktop with a downdraft. You should always buy separate exhaust, preferably an up draft. You don't need a built in griddle. Lay a cast iron griddle across 2 burners.

My first induction cooktop was a 36" Miele that I put in with a remodel. I loved it. My new home that I am building will have a 36" GE Profile induction. The builder will only put in GE. I will be happy with it. They all work the same way.

I have decided on a wolf 36" induction cooktop with a telescopic vent. The vent will use the same concept as the old Jenn Air downdraft system. They are going to place the motor for the vent under the floor to make the kitchen a little quieter. So far I like the direction we are going.