I'll just throw in another, 'Yes it'll work' anecdote, as I took my BB 8700c with me last year on a 10 day trip to Germany and it worked just like it does here at home -- except my bill was $300 more than it usually is. Keep in mind I also (stupidly) used my phone and my husband used his phone for voice calls. My in-law's also used our phones to make calls home as they have Verizon and left their phones at home. Thankfully, my father in law picked up the tab (the trip was his idea) on the extra $300.
It was soooo handy dandy to have it with me. I was on a family trip but was able to stay in touch with work while gone which was important as someone important resigned within one of the organizations I cover (I'm a reporter) and I was able to communicate with him via e-mail while my boss was still trying to figure out who would write the story. Heh.
BlackBerry on GSM service, IMHO, rocks.