I actually got a response from kingwa about the differences and he basically said the 28 will sound like a balanced amp and the 29 will not... from my experience with balanced setups if you gain a little bit in sound stage/dynamics with some circuits and with some others the difference is nonexistent... though he again stated that I should get the 28 if I go balanced because the 28 in single ended mode will sound worse then the 29, and the 28 balanced vs the 29 single ended will be close, but the 28 will sound a little better. SO go for the one that fits what you want to do. I don't intend on re-terminating all my cans so the 29 was my first choice.
Interesting, thanks. Leaning toward the 29 a bit more now...