It's encoder with an "e", first of all. Sorry, grammar rant over.
Personally, I have found that the mp3 encoder doesn't work that well. It makes my stuff sound really odd, whereas if I export it as a wav and convert it to mp3 in iTunes, it sounds like I think it should sound. I don't think it's my settings, unless the encoder doesn't like VBRs. Anyway, the point is, you might be better off just converting it after the fact.