I'd definitely switch if they'd enable FaceTime over 3G. Hotspot functionality is almost worth it esp. if it includes unlimited data (I know, jailbreak and you get both )
Here's food for thought... On EVDO you can't EVER have FaceTime over 3G since it sets up the call as a voice call then converts it to data... you can run simultaneous and do the handoff on GSM\HSPA, but not EVDO. The only way they'd be able to make it happen would be to remove the "Facetime" during call button. No handoffs... see already people are taking the voice + data simultaneously for granted. And you won't be able to HOLD your phone call to listen to a voicemail because it won't download until you hang up... same with pic messages. See ATT not so bad now ehh?