I'm a mechanical designer for automation and have designed some high-speed moving pick and place units using carbon fibre tubes. They're very rigid - and any vibration dampens very quickly. As for wear... I'm curious to see what kind of bushings/bearings are on the print head (igus bushings?). It seems like a good way to go but I've yet to see any really close-up detail photos of the exact configuration of the X/Y H-frame.