I know what you're talking about.
A few guys have posted about how the TransGo ruined their trannies. Thats a very small percentage, and there's no proof that's what caused the breakage.
Then there is Jerry W., who designed the 40R70W, he says that the TransGo is terrible, but didn't quite explain how it could ruin a tranny. The shop I went to does ALOT of TransGo installs, he says he has never seen a problem from a TransGo.
10,000 miles on mine, going strong.