I wouldn't upgrade in that circumstance either, unless there was a viable program like PDAnet available (I have used their stuff with the treo DUN and it works great).

Other concern I have about the upgrade is that I understand you are forced to upgrade Activesync as well, and the latest version of activesync doesn't allow you to sync (to your own main PC) wirelessly. I love being able to sync from anywhere in the house to the pc with the primary partnership and don't want to lose this feature.