I actually sold my XV6900 and moved to the Omnia, which I hated it's keyboard and lack of custom ROMs/GPS, so I returned it and got the Touch Pro.
The XV6900 has a serious issue because of it's white housing. The housing cracks like mad even when protected by a hard case. I went through two of them in less than 6 months because of the cracking. When the 2nd one started cracking in the exact same place ( see post at
http://forum.ppcgeeks.com/showthread.php?t=27355 - lots of people having this problem!), I decided to upgrade before it got any worse.
Great phone though - very customizable. If you can tolerate the rediculous cracking, go for it!