I'm building a new house and am planning on doing a Pex "Home Run" system with individual water lines serving each fixture in the house. It's a small house with a centrally located water heater, short runs, only a few sweeping turns and very efficient low flow fixtures. It seems like an ideal situation for 3/8" pex branches allowing for quick delivery of hot water with minimal wastage. I've already calculated the friction losses in each 3/8" pipe run based on the flow rates, length of piping, number of turns, resistance in fittings and head losses and they're quite low. I have no worries about pressure and flow using this size pipe. I'm trying to figure out exactly how I'm going to terminate the 3/8" pex at each fixture since I'm very limited in my selection for 3/8" parts. After looking through the parts catalogue is see two options (Each option uses a sink as an example): Option 1 flow path: Start at 3/8" crimp fitting branch in the manifold Continuous pex run without fittings all the way to stud cavity behind sink 3/8" crimp fitting to 1/2" copper stubout 1/2" sweat stop valve to 3/8" male thread braided flexible supply line to threaded connection on faucet Option 1 means I can go with a simpler manifold without valves on each individual branch. There's also a rigid copper pipe making the transition through the drywall which I prefer. I don't like the copper to pex transition inside the wall, especially since a few of these connections will be in an exterior wall (on the warm side of 12" of insulation, however). Option 2 flow path: Start at 3/8" crimp fitting on branch valve on manifold Continuous run of 3/8" pex without fittings all the way to stud cavity behind sink poke the pex pipe through the drywall and up towards the faucet connection use a 3/8" crimp fitting to female thread adapter and install on male threaded faucet connections Option 2 will have several disadvantages like requiring valves on each manifold branch since there won't be any shutoffs at the fixture end. It will require fewer transitions and no buried connections but the pex will be exposed and vulnerable outside the drywall running all the way to the faucet. The piece that adapts the pex to the faucet has female threads that are made of plastic. What are your thoughts?