Anybody know if there is any merit to the idea that Centerlock rotors are truer than 6-bolt?
I dont know, but I've got 6 bolt out back and centerlock. I personally think centerlock is one of those things to make you buy something new. I will say, while working on my bike at home, centerlock is a heck of a lot easier to deal with because you just drop a cassette tool in and pop it off VS having to take an hex key to each and every bolt.