If I was into replaying the game, I'd probably do it. If ME1 was out on PS3 and had trophies, I'd be even more likely to have done it, as for some reason I find trophies more fun to collect than achievements. I don't know why, I just do.

I agree with the whole immersion thing and trying to play out how I would be in the situation rather than doing something just for the laughs you can get out of it. My first play-through will always be as a good guy as I actually enjoy being a good person, so it makes sense for me to be a person I enjoy being in the game - at least for the first play-through, anyway.

I very rarely replay games, though, especially on the 360. Maybe it's the controller or the layout of the operating system. Dunno, I just prefer the PS3 trophies, so am more likely to replay games on that. And even then, only a couple of them have been replayed so far.