floyd landis used the power tap SLX (not currently released), it's a wireless version of the powertap SL. I like power tap, yes it does claim to be a little more precise, and measuring at the hub instead of the BB does make more sense to me since it's closer to where the power is relayed to the ground thus eliminating sources of error like the drive train. I like my power tap cause i can switch my wheel between bikes in under 5 minutes, i sure i had to buy another 50$ wirring harness for the second bike, but the big thing is that with that 50$ extra harness i'm able to move my yellow powertap computer, and powertap wheel to any bike i want very quickly. So if it's rainning or snowing out and i want to ride my beater bike, instead of my nice carbon bike i can swap wheels on the two bikes and i'm ready to go. SRM does have the freedom of using anywheels isntead of wheels with a powertap hub, but powertap wheels are growing in selection. I don't see the logic of comparing the price of an SRM alone (over 2000$) to a powertap sl (1000$ with set of basic mavic wheels), even if you buy another another set of carbon wheels w/powertap for 2000$, you're at 3000$ and you have 2 wheel sets. 3000$ most likely will not get your an SRM a basic set of wheels, and a set of carbon racing wheels. So to me powertap is cheaper.

Additionaly there is the problem that cycleops has yet to put out a disc wheel powertap option, well, you could always purchase a set of zipp 808's or 606's. The rear (85mm?) deep profile is supposed to be as close to a disk as you can get these days, but it offere's of the advantage of being race legal in all road event's, not just TT's. Just something to consider.