At Outlaw you have time and facilities to change, so its worth being comfortable. I swam in speedos and wetsuit, went for tri top and bike shorts on bike, and switched to running shorts for run. Prob an extra 5 minutes in transition overall, but I thought it was worth it.
Jonny - I had arm problems (tennis elbowish thing) last year before Outlaw. May be worth doing more leg drills and less on arms for swimming for a bit, and look at careful stretching or exercises. The only thing that will make your swim more difficult than it is at the moment is pushing it and really bending something.
SlokeyJoe - yep, I'm at Leeds. Only doing the sprint, though - Olympic was sold out.