Tan, not disagreeing with you at all, just mentioning - ever seen Shane Hammond squat? There's a video clip on Freaks-O-Nature of him squatting 1008 and the entire lift takes him about a second. The guy is an absolute freak.
I usually don't worry about tempo. I use a controlled eccentric and an explosive concentric. I do try to keep track of how long the concentric takes though... you don't want the concentric to slow down, speed is key when you're talkin function strength. The only time I really worry about tempo is during static overloads or heavy negatives.