Hypersmurf
Moderatarrrrh...
As for the S&S rules ... puh-lease! What fighter type is going to have a reflex save high enough, even at twentieth lvel (let alone 10th), to meet a DC of 36 ... ?!?
There's always Monte Cook's suggested opposed Tumble roll - Tumble vs Opposed Attack Roll.
(If the attack roll beats the Tumble check, it is not used as the attack roll for the AoO; it only allows the opponent to make an AoO. If he elects to take it, he makes a separate roll for the actual attack.)
This has the plus side that more dangerous opponents are more dangerous to tumble past, but the minus that in most cases, Strength makes more of a difference to being able to AoO a tumbler than Dexterity or Reflexes.
You could always follow the new Feint vs Sense Motive + BAB model, and make it Tumble vs Reflex + BAB...
-Hyp.