Upgrade from 2.5 to 2.6 and later?

Are there any issues I should be aware of in my migration? For the most part my installs are PBX-In-Flash (FreePBX 2.5) with Sangoma a101D cards

I started my test box (Digium POTS based card) and began migrating from 2.5 to 2.6 with the uprgade tool. All seemed ok, although I had to re-run genzaptelconf. Or at least I think I did. The system would not answer incoming calls - nor allow outgoing ones beforehand. All seems well.

As I understand it later ones use Dahdi. Will this cause issues? With My Sangoma Cards? Are there other problems I may encounter?

Any hints are appreciated!