Hi Michelle,
It is certainly easier to feed cats the same food, and on the same schedule, if possible. (I allow my 6 cats to free-feed wet food.)
Most of us here feed our diabetics kitties low carb wet food, and fortunately, that diet also suits most other cats too, so that makes the job a lot easier.
I used to feed all my cats dry food until my Bertie became diabetic, and then I soon learned how much the dry food was elevating his blood glucose and contributing to his being dehydrated (cats have evolved to eat a wet diet (birds and mice etc) and often don't drink enough water when they eat dry food).
And I was pleasantly surprised by the improvement in the condition of
all my cats when they were switched to low carb wet.
I'm glad your kitties have good teeth. And I can certainly understand why you may not want to mess with their diet if you think switching foods will change that. You may, however, be interested to read the following info from vet Dr Lisa Pierson. The following section from her catinfo.org website is about dental health:
http://www.catinfo.org/#Dental_Disease
Best wishes,
Eliz
