It's visually pretty much the same.

The 36" will work better, no matter what your heat source. It'll also have better lighting and the cabinets on the sides will need less cleaning simply from being further.

The 30" will be cheaper and probably about good enough.

Cooking plumes expand as they rise, whether from gas heated pans or induction heated pans. While the plume shape and velocity may differ in the two cases, for full capture the hood width needs to be wider than the contours of likely pans on hobs. Go with 36-inch unless performance has no significance and the hood is intended to be purely decorative.

What Fori and Kaseki said +1. Also,the 36" Tempest is (IIRC) only about $50 more than the 30" model so downsizing the hood doesn't save much.

FWIW, I think your chosen model (Zephyr Tempest) is a more capable choice than, say, the shallower, flat-base Zephyr lines such as its Breeze and Cylcone models. A dozen years ago, I bought a 36" Cyclone model because my old-house kitchen has spatial limitations that require a slimmer hood. (I had neither the budget for nor interest in replacing the existing antique glass front kitchen cabinets which would have been required in order to fit a taller hood.) My 5"-tall, flat-base 36" Cyclone model has been more or less adequate over both gas and induction but, from what I've seen of the taller Tempest model that a friend recently bought, the Tempest seems noticeably more effective as well as easier to clean.

“We are less concerned about venting capabilities of a 30" v 36" since we are doing an induction range over a gas range.”

I have seen this thinking mentioned before on this forum, and I always wonder why people make the mental leap that an induction cooktop would not need as much capture area or needs fewer cfms. Cooking a hamburger, bacon, stir fry, or anything else that creates smoke and/or oil splatter will have just as much smoke and oil splatter whether cooked via induction or gas.

Many people cannot have a 36” hood over their 30“ cooktop because of either existing cabinetry or they cannot forego 6” of upper cabinet space in a smaller kitchen. You do not appear to have those constraints. Therefore you should definitely get the 36” hood.

Cooking, gas or induction, can produce a lot of VOCs, PM and Carcinogens. You need good ventilation for induction just as for gas.

More: https://bamasotan.us/range-exhaust-hood-faq/

I'd definately do 36" for ventilation but personally I think it looks better as well.

We installed a 30” over our new induction range (400). Were very happy with it.