I just decided to read the reviews for the phone on t-mo.com (sort of the final step before I buy one after work today just to make sure there aren't any massive issues people have been reporting that I've missed) and I have to say, and I apologize allgamer because this is sort of off-topic, they were ****ing hilarious.
One guy claimed this phone should not be advertised as a non-LTE phone because it is a LTE device (huh? HSPA+ is definitely the same as LTE...waaaaait...). Another claimed that because there was no wifi calling, you couldn't surf the web on wifi! OH EM GEE GAIZ U CNT SUFR TEH WEBZ! Wait no...My Nexus S can't do Wifi calling and I can (and do) use it on WiFi all the time. Same with my Epic 4G. Same with my Evo 4G. Same with my MT3G. Same with my wife's Evo Shift 4G. Same with my Wife's Nexus S. Wow, I guess samsung must have really screwed the pooch or something to make it so that wifi calling was linked to all wifi use. Yikes! They better fix that soon! (That was sarcasm, FYI).
On a serious note though, I've done the reading, compared to the Amaze and watched the Galaxy Nexus launch and I'm not convinced any of them are or will be better than this phone on t-mo. The only real huge selling points of the GN (compared to the SGS2) are the HD screen and ICS; we'll get ICS and .15in diagonally larger isn't really that much so oh well. As for the Amaze? Its really only got better resolution which I couldn't find an issue with in store and I have pretty discerning eyes. Yes, I could see the difference but I couldn't see it making an impact on my daily life.
In summation, and as a non-owner of the SGS2 I'd have to tell the OP that yes, you did in fact make the right choice!