I would place good money of PEX pipe it is a game changer. The thought process behind PEX is that the pipe may be smaller and move less water, but it requires less 'hard' bends i.e 90 degree corners. so it is much more effecient.
I think you lose 15% of pressure for every 90 degree turn. Which racks up.
When running from one 2nd floor to the first I can eliminate 3-5 90 bends. for example
PEX also expands up to 300% and can return to normal operating size.
I also recommend not using the plastic fittings but go ahead and grab the copper fittings with the copper crimp rings.
I believe PEX has been around for 30 years and is gaining ground in popularity in the right applications.
"You can't just give up hope and walk away, Cause when you do that then there is no hope at all."