Is there a "recommended" list of PIMs that can be used successfully with GMS? I currently have users with a variety of devices and none have been especially problematic. As we move forward with a larger deployment I'd like to point users to a couple of solid performance choices. Verizon is our carrier and my options are:

Motorola Q (WM 5.0)
Palm Treo 700P/WX (either Palm OS or WM 5.0)
Samsung i760 (WM 6.0 Pro)
VZW XV600 (WM 6.0 Pro)
Motorola Q9M (WM 6.0)
Palm Treo 755P (Palm OS)
VZW XV5800 (WM 6.0)

I'd like to standardize on Windows Mobile though I don't know if there are any compatibility issues between WM 5 and 6 that would affect GMS.

Anyway, any thoughts/recommendations/warnings would be appreciated. At least GMS is working consistently for the users and one less thing I have to deal with!!!