Hi,
I also have the Xterra Sleevless Vortex 3, $99. The water can be cool here early season but it warms up fairly quickly so didn't think I needed a full-sleeved as I don't swim OW until its in the 60's and get warm fairly quickly.

I'm not a fast swimmer and like that it gives me an extra level of security and more bouyancy for the legs as tri-girl mentioned. Once you get used to it they come of fairly easy (lots of super-glide on the feet) so doesn't take much time in transition. Around here 90% of people where wetsuits for tris so not much of a disadvantage and the water rarely gets warm enough for it not to be a wetsuit legal race.