You have to be able to open or pull it up to do repairs. Warranty could be voided if you use a sealer or caulk under the top

Thanks, that's a very good point ... after just checking the installation manual it turns out that it also applies to the cooktop if it's top-mounted.

I also just stumbled across another thread that indirectly addresses my question ... it appears that one potential worry is the skill of the stone fabricator, and another is crumbs getting in the crevice.

Here is a link that might be useful: Miele Induction Cooktop: Set Flush or Drop In

I'd worry about crumbs getting into the crevice, myself. One of the things that I love about my Miele cooktop is that there is no place for crumbs to get stuck. I don't find that the unit sticks up far enough to cause any problems.

Cj