Eric,
I once saw a comment by a Taipa sailor that the uni-rig doesn't want to go as well with the traveller centred. Kirt said much the same thing when I singlehnaded the Taipan at springfever 2002.
Put it off centre about 3 to 4 inches.
Also the Taipa main seem to prefer to be hooked in the uni-rig configuration; alot of sheet tension. Kirt told me the same thing at springfever and sure enough when I did these things the boat pointed a few degrees higher.
All thse things feel unnatural but they do work.
Maybe you should try these too.
Wouter