Originally Posted by snrusnak
Well I personally don't know for sure but I don't believe that was the whole reasoning and benefit of PEX. I believe the benefit was just to have a truly flexible piping system. Not necessarily because it limits pressure drops from hard bends. As I said before pressurized systems have little pressure drop from hard bends, it's basically negligable. They call it a "minor" loss, as opposed to a "major" loss. If it were not pressurized then it'd be a problem.
I really think PEX was just a different sytem someone came up with to make a flexible system, and in all honesty, in the end it is just their invention to make money lol. Just like everything else. PVC was the same, it was a new invention of a system to use in lieu of copper. I'd say all three systems have benefits and drawbacks, and all will work fine overall. I tend to use whatever is coming out of the slab just for simplicity and uniformity. If I was plumbing from scratch I'd use either copper or pvc, though it'd likely be pvc as it's substantially cheaper. I'd just use copper at tubs for the strength and anywhere the pipe passed through mortar, masonry, concrete, etc (unless covered/protected) as cementitious products react poorly with copper and will degrade the pipe.
PEX was made to take place of copper and pvc. its cheaper and faster to install. PEX does not break if it freezes as it expands and contracts with temperature unlike copper and pvc. Copper is $20 for a 10' pipe where PEX is $25 for a 100' roll. Yes, the sharkbite fittings are more but you use less fittings since pipe is flexible, and as far as the long bends...false, PEX can be bent is a tight U shape about 6" diameter as it is used between floor joists for heating and so on.