Originally Posted by nav
1:1 ratio: 3.0 (entry level), SX4, SX5, X.9, X.0 (top of the line).
2:1 ratio (Shimano compatible): Centera (entry level), TRX, MRX, Attack, Rocket (guess).
You forgot X.7 between SX5 and X.9
Basically for comparison to Shimano:
XTR = X.0
XT = X.9
LX - X.7
Deore = SX5
Alivio = SX4