Scott, I have a full batten on Shanti. My biggest complaint is the need for slides that rotate so they don't bind when going up/down. I will be installing a Tides Marine track to solve that problem.
The problem with "the best modern Dacron" is it is as stiff as a board. I have Marblehead and it is rated as one of the best. But it is damn near impossible to flake nicely.
I have really enjoyed the performance with the full batten sail. But if I was to buy anther sail at this point I think I would stick with a battenless main in a softer cloth. Problem with that is you need a sailmaker who can build without a hook in the leech. That is the main reason I went to full batten.
From what I understand, tan bark sails were originally made to fight UV damage. The colored cloth does not allow the UV to penetrate the cloth as deeply, thus lasting longer. Do some research at the manufacturers of sail cloth.
Good luck. Let us know what you decide.
US Virgin Islands