The PEX question

No doubt this has been discussed, but a search of the site didn't turn up anything.

I am a remodeling contractor, and I've sweated a lot of copper joints over the years. PEX is new to me, but my plumber has insisted on using it in a current high-end bathroom remodel. Because of the complexity of the shower wall (regular shower, hand-held, two body sprays), and the trickiness of mounting the valve bodies, an access panel on the back is unrealistic and wouldn't be particularly useful.

I have full access to the lines from below, but once that shower wall is boarded up and tiled, that's it.

I've read about the class action suit against Zurn, and other horror stories, but nothing conclusive. Advice, please?

I have only until Memorial Day to get this thing fired up. Thank you in advance for any comments.

I've been using Uponor/Wirsbo.
What pipe does the plumber use?

The fact that he is using PEX is not as important as whether he is compensating for the reduced i.d. of PEX, given the complexity of your installation.

The Zurn issue was bad metallurgy in "brass" fittings made in China. Combine those with the toxic drywall they shipped here and you have a lot of laughing, wealthy Chinese capitalists.

The volume will be an issue. Hansgrohe valve bodies only accept 1/2" NPT, so the best I can do is run 3/4" PEX to the thermostatic valve. I figured the short runs of tubing to the rest will help stabilize the assembly, but I still plan to strap the snot out of it. Unbelievably, Hansgrohe provides no ears or other fastening points for the valves.

Volume is a concern, indeed. The thermostatic valve is rated as delivering 18.5 gpm with its 1/2" inlets. I may be replacing the well pump, however.

I'm not sure if the plumber is using Wirsbro, but I know it's not Zurn. I'll find out today which brand.