Apologies for grave-digging, but if you're still looking at track PMs, Stages did make a DA crank based system which I'd heard some okay reviews of, and for my 2c, I've had good luck with the PowerTap track hub, as has a training buddy of mine. Obviously you don't get to use it when you put a disc wheel on the back for your A races, but for training and geeking out on data purposes it's been good and seems generally accurate - paired with my old Garmin 510 mounted under the saddle, and using GoldenCheetah for analysis. You do have to buy the special White Industries style splined cogs for it, but a 13T and 14T are enough, for most things really... 15T if you want to warm up on it
I wish they made a 12T though....