my suggestion. just leave them in gt form. the damage increase will be very slight. in the future if you rebuild your sin your dex requirements will be way low (36 pts less) which can add up to 108 extra life.
Only upgrade uniques and rares? Thanks for that answer. If I upgrade a rare will I be able to keep those +mods already on it? I was planning on sticking some points onto Dex anyways so I would be able to use a Hel'd Widow Maker on my Lightning WW assasin. Currently I have one that is pretty perfect in stats. But I'm currently uber tristing another WW Trap sin with more dex to be able to use the Widow maker. Does this seem like a good idea?