I see what you're getting at. I use stock Shimano 105 SPD pedals. After a bit of searching, I'm not sure how they compare to others, but I have considered putting a washer between my crank arm and pedal. My fitter said I'm biomechanically-inclined toward a narrower Q-factor though, so that wouldn't be ideal even if the new angle does fix my knees.

I have a GXP BB lying around, so if I can get some evidence of greater ankle clearance on GXP cranksets, I might go that way. It's no BB30, but the next cheapest fix would be a new frame.

I might start a thread on GXP in comparison to my Powerspline junk with some photos in order to avoid derailing this thread.