I got my supplies from BR, but I had to get a couple of quotes. I was not going to use 5/8" pex. I told them I had 3/8" reb 1ft on center and WANTED 1/2" pex, yet they still quoted 5/8". I gave a nice drawing of my layout including a shower and toilet and they never even avoided either. A major no-no by the way. Their loop lengths WERE NOT within 10% of each other. I ended up down loading a copy of LoopCAD and using the free trial to layout my shop. It took a few days of playing around to figure it out, but I now have a decent layout that meets my requirements.
I believe BR has a couple of miles of 5/8" pex that they can't sell, so thats why they are quoting with it.
Wedge