No.
My personal conversion to True20 is total.
That said, D&D is certainly one of the first systems I'd choose to work with if, for some reason, True20 wasn't the best suited.
That said, I have yet to come up with a concept for a game that I would want to play or run with something other than True20.
I guess you could say I have a hard time suspending my disbelief when some people (say, level 10 fighters) can 'safely' fall 30 feet onto solid rock five times in a row and then get up swinging, while one such fall could be reasonably expected to kill any average peasant...
Or, any mortal (for example, a ~15th level barbarian) can stand swimming in boiling water for half a minute (10d6 per round [35 average], 5 rounds, 175 damage...and the average barbarian that level has maybe 200 HP when he's not raging).