Defiantly agreed about living with the decisions. I'm not much of an RPG gamer (though between Mass Effect, Dragon Age and Fallout I've probably played more in the last few years than the previous twenty) but when I do I always go with my gut on the first play through. I think it's even more important with ME as you'll get to carry all of those accumulated decisions through the entire trilogy.
That doesn't mean to say of course than I won't tailor things a little in later play-throughs.
All told I think I have about 6 Sheps (one of each class) though most are femsheps (much prefer Hale's voice work.) One even boned Kaiden against my better judgement...just for the sake of doing something different. I think I only have one that I didn't finish the ME2 play through on. Aside from being a little burnt out of the game by the time the Arrival DLC...um...'arrived'...I plan on saving that one until the lead up to ME3.
As far as *THAT* decision goes (he said trying not to spoil two things for DH in as many days) I think my main Shep made the right call. I had a feeling doing otherwise would bite me in the arse.