Steve, Keep an eye on the connections between the 2 different metals. Any time 2 different metals contact, you can set up a localized "corrosion cell"
I didn't want to mix the metals but couldn't get every thing in either galvanized or brass. Articdude is right, Pex is being used too. Now that I've done this it may be that I will do it over in Pex. I put a union in the long manifold so it is easy to take out now. Just about ready to pressure test.