Having messed with the hard PVC though I've become an increasingly big fan of flexible hose myself. It's not cheap at the larger diameters, and you have to be aware of the possibility of kinking but there's no cutting or gluing, it doesn't vibrate, rattle, or crack, and it's easy to take apart if you have to for some reason. I think I may try a compromise and go with spaflex the next time I put a tank together myself. Hard piping is just a real pain in the buttocks if you are working in a confined space.