I've never used the u620 but it looks like a pretty slick phone, however, I hate Samsung's bluetooth implementation (I hated the a930, a870, a970 all because of that, funny but now I'm looking for an a990). You might want to take a look at that again. My only advice would be to avoid the KRZR. It looks awesome, but the UI is unbearably slow, it takes 3-4 seconds so simply open the main menu. I would say that if you can stand using the 8500's touch buttons stick with it, I almost regret returning mine after I have spent some time with the KRZR, well at least my i730 should be here by Friday. Good luck
-z