I heard that the tapered spindle in the Exustar would be difficult to work with, giving as much as 15% variance in power readings. Since Garmin is sourcing the pedal from a third party vendor, unless they bought the company or they spec'ed a full new design the pedal will retain that weak link. The only programmatic solution would be to work out some algorithm that would predict the variance and calculate it out.

Look's power pedal has a much beefier spindle at the end, made specially for the power pedals. Therefore their power pedal is a bit clunkier than their normal one. This reduces power variance to 2% or so (less maybe), which is about what people expect.