Based on the experience of iLounge’s editors, users moving from original iPad 3G units to iPad 2s with AT&T 3G hardware may experience AT&T service problems. During testing of two AT&T iPad 2 units, iLounge discovered that the unit registered with a prior AT&T data service account refused to activate on AT&T’s network, despite full payment of the company’s $25 service fee using the device. The second unit, registered…