Had my wiz open these items in the Craft Arms/Armor interface b/c I wanted to rename them to suit the chars using these items. All 3 of these armors showed +1,+2,+3 ALREADY HIGHLIGHTED (i.e., these traits were a different color blue and were unselectable.) After renaming ALL were +8 base AC/dex bonus unchanged. Green chain went from +6/+4 to +8/+4; purple from +7/+4 to +8/+4; and L's Plate from +6/+3 to +8/+3. I can't recall but I may have had to select the +3 trait and click the craft button - but I'm sure that his did NOT cost any gold or experience.
Holy good AC Batman!
On a side note - SPOILER - having a buckler equipped allows me to right-click any shield (so far, anyway) into its place even if I have a off-hand weapon equipped at the same time. I've only tried this with my dual-wieldinG ranger though. The cheese factor on this one is a little high for my taste, but it seems to me that all the elven chains really ARE +3 if you only look at them hard enough...
This is all post-first patch.
Cheers!