No, I havent tried Bontrager myself. I dont like the powertap concept, you get the inconsistent data because its on the other end of the drive train, and you loose important data when you change wheels, or you have to fit every wheelset with a powertap and their by spend more money. I change frequently between high and low profil wheels.
I would have gone with the pedal based if it was available last year, but I didn't have the patience to wait for them, and it looks like you are forced to run a specific clipless pedal system depending on you powermeter. I very happy with my power2max. Changes in temperature does show, but can be nullified by zero the system. Which is done by not pedaling for 2 sec. So not an issue in my eyes. If I was a pro I would go for the SRM but don't have the money.
If you can afford Enve, you dont have a choice to make
Yeah I saw the ENVE cost and said "Hell no." I'm thinking of the Zipp 303 CC, night weight, great aero, and braking performance that will do me well in college if I end up at the one I want to go to in the mountains... Climbing sucks, but its my weakness and I have to train it ! I'll be buying a complete power kit, in other words, headunit, and meter all together, so that wont be an issue.
You do lose 2-5 watts with drivetrain flex... I'd love an SRM but I'd have to change my choice from SRAM to Shimano. for aesthetic purposes (I realize how petty that sounds). So I'll stick to quarq or possibly the pedal based systems if, on release, they show to be plenty accurate in comparison to powertaps then I'll consider them as well.