We have a handful of attorneys on them who just don't care about the tech - there are some 7230 users here that are very happy with the device and see an upgrade as a waste.
Conversely, there are a few attorneys here who cyclically upgrade to every new device when they come out.
The upgrading type do outnumber the non-upgrading type, for the most part.
The average user here doesn't want to spend their own money on the units, so they end up only upgrading within the plan we have, which is about every 20ish months as it turns out.
We have had a bunch of people upgrade for a specific feature - usually something like the Pearl's form factor, or a 7100 user who wanted to go back to a Qwerty keyboard.