Yes -- you can mix IAP models within the same group.
There is a caveat:
IAP-92 /93 are limited to qty. 16 IAP and 256 concurrent connections per group. Additionally, if you have an existing group of other IAP models (not -92 / -93) then introduce an IAP-92 / 93 to that group, the whole group will be held down to 16 IAP and 256 connections..
This only applys to the IAP-9x. All other models are unlimited in the number per group.