Hey, I agree with you - I chose the manual because it is so good and much better than the 6l90e in this car. I do like the 6l80e in my 6.2L
Sierra though....not for a performance car though. Any new trans is going to be expensive to replace, and GM has its share of problems with this just like every other manufacture. It is not just about ultimate shift speed, it is about the quality of the shift under load and the ability to skip gears on downshift as well. How the trans responds to paddle requests....alot more than just the shift speed.