I have two specific concerns and questions about updating to WM6. First, a little background. I have an AT&T branded Treo 750 (locked to AT&T) that has been upgraded to WM6 using the original leaked ROM. No complaints, it works great for me. My questions are related to eventual upgrading to the official released WM6 and staying current with AT&T HSDPA rollout.

1. I read that to back down to WM5 there was a specific process to follow with the first step being to unlock the extended ROM. Failure to first unlock it might cause the phone to be bricked (or so it was said).
Question: When upgrading from the leaked ROM to the official ROM will we have to unlock the extended ROM first too?

2. When I was on Sprint there were times when you couldn't get service when traveling because the network got upgraded and older ROM versions couldn't recognize the newer service. The solution was easy -- you just went to the store and had them update your ROM. Something similar happened to me last week on a business trip. My Treo with the leaked WM6 ROM could not make any data connection in Atlanta or Dallas (phone service was fine). When I came home (St. Louis) the ability to make high speed data connection was normal.
Question: Is AT&T's service similar in that periodic ROM updates may be necessary to stay current with service (i.e., tower) improvements across the country? And, will I have to wait until the official WM6 release to get my phone current (as I refuse to go back to WM5, even temporarily)?

Thanks in advance, and sorry for the wordy post.