I think its all in how you drive it. I DO know that powershifting the T5 at any power level, even stock, is asking for a new TKO.
Ford put commands into the computer to actually pull timing (IE Power) during shifts to prevent shocking the tranny. This is why your cay will fall flat on its face when grabbing a gear the stomping on it. Powershifting bypasses this effect and WILL break your T5.
Adam