Let the hive mind of Engadget get that for you.
"I just switched to Sprint from Verizon about three months ago for the Pre. Then I went for the Hero about a week ago. Now, I miss my hardware keyboard and am thinking about switching to the Moment. I am still able to switch back to Verizon if I want and get the Droid when it arrives. Should I just trade up to the Moment when it comes out, see if I like it, and if not switch to the Droid? Or something else entirely? Help!"
The standardization with LTE is a good thing, but already, a large chunk of the world is on the 2100 3G band (including DoCoMo and Softbank in Japan) - with the notable exception of North America.
America, by definition, must be different!