Download the installation pdf off the AJ Madison site for the models you're considering. They'll have dimensions of the cutout and likely a picture of the template. You may need to get a counter fabricator to come out and make a cut on your counter to fit the new template. An appliance installer won't always do that. Get the right person and it won't be a problem. I'd prefer the Bosch.

Anytime you change appliances, you can expect in sizes for cutouts. DWs come closest to a standard 24" width, but width, height and depth can all vary a bit. Cooktops and ovens are probably the least standard.

You don't necessarily have to remodel your whole kitchen, buy you certainly may have to recut the countertop.

We had to have a carpenter put small strips of oak in the former cutout when we replaced a GE with a Whirlpool. Cutting granite is not cheap but it won't break the bank.

I had to re-cut our granite last year. I will copy my experience below. I am assuming that the new cook top is bigger rather than smaller. If smaller, either a little shim of wood could be screwed in (not sure of method of attachment), or an insert frame can be made by outfits that do it.

When I replaced mine, I had to increase the depth because my new cooktop
box was one quarter inch deeper, requiring the pop up vent to be moved
back. I found that I could cut the granite myself. It wasn't as
difficult as I originally expected. I happened to have a little
tile/stone/granite cutting saw that looks like a baby skill saw and also a
grinder. One needs both and some plastic to hang from your lights or
something to catch flying crud from the grinding dust/mud. I used wet
cutting by attaching small tubing from my faucet to the saw. This
required some plastic below funneling into a bucket to catch some of
that water (slow flow)! Actually, it was so little that a towel would
have sufficed.

Here is the link I just copied from. I have more info further down and others have useful pics. I think that you could actually use a regular 'skill saw'. There are 7" diamond blades for them. It wouldn't spin as fast as a 4.5 or 5" stone or tile type cutter like I had, but it would still cut way faster than you would think. It would probably be better to rent one for a day instead though. Of course, if your handy spouse or whomever doesn't have both the skill saw and a grinder, then the borrow or rental route is needed anyway. BTW, all my crud protection could be skipped with a handy helper to hold a towel in front (and perhaps pump water on the cutting path while you cut.

I also had some old granite scraps to practice on and to see that it was much easier than I had imagined. If you didn't keep any, maybe you can get a piece from a second hand store or scrap yard.

There is something else to consider: the granite needs. It may be that you have the space within the cabinet for the appliances to fit, however by the time you cut out the hole to accommodate the appliances, the granite may not have enough material between the hole and the edge of the granite to keep the granite from being vulnerable. I believe it is optimal to leave at least three inches of granite (maybe more) between the granite's edge and the cutout hole.