The installation of the PEX was pretty straightforward after getting the shower valve in, except you have to be careful to plan ahead and not plumb yourself into a corner where the swaging tool can't operate. I only had to take out the rear section twice because of this. The good news is that you can carefully cut the copper rings and take the PEX apart. This was particularly important (the planning ahead part) in the rear compartment under the sink.
You can see that the PEX installation is much simpler, with only two dump valves (visible in the rear compartment) compared to the previous six! The bends were a natural--no 45 degree fittings! It was a real piece of cake to snake the lines under the shower up to the front sink and around to the street side toilet and water heater. And the shower is back together! I still need to trim it out a little and get a plug for the old shower flex fitting hole, but it's functional.
One very big consternation is getting the 3/8" FIP toilet fitting adapted to the more standard 1/2" MIP found on faucets. I'm finally pleased with the simple 3-piece adapter shown here.
I like to have a valve for the toiler for the simple reason that the toilet valve is EXTREMELY sensitive to cold--I think it freezes solid well above 40 degrees. So even when I'm willing to fill the rest of the system when the weather is cold, I blow the toilet lines out and turn it off and keep it dry, using jug water to flush and a little anti-freeze in the holding tank.
The PEX continues around the rear compartment to the street side to service the toilet and water heater (not shown). I left some short lengths of copper on the water heater--I figure the heat conductivity in the pipes near the water heater will keep them from freezing in any weather.
Zep