Is this OK? rough in valve

[FJK]

I'm replacing an old, simple Moen tub/shower rough-in valve with a new Moen posi-temp valve. Due to space limitations of a vent pipe next to the rough-in valve, I need to come out of the cold side of the valve with a male/female 90° fitting (solder in). Is this OK? See image 15. Image 16 shows the new valve mocked up off the old valve's tub spout to indicate why I need to come out of the valve with a 90.
Finally, image 12 shows the existing plumbing that has air hammer risers & the close proximity of the vent pipe I mentioned earlier. I plan on eliminating the risers when I install the new rough-in valve. Any comments or plumbing routing suggestions for image 12.
Thanks, FJK

[jadnashua]

My unprofessional opinion, you'll be fine. Note, those air chambers typically become useless after a few months unless you shut off the water at the main, then open up the valves and drain the pipes. The air trapped there gradually gets absorbed. You shouldn't need them, but if you want a water hammer arrestor, put in a real one - they cost about $12 each at a big box store.

[Redwood]

hammer arrestors cannot be buried in a wall!

[Bob NH]

Remove the internal parts of that valve before soldering. Should be nothing but metal in there when it's hot.

[Rancher]

hammer arrestors cannot be buried in a wall!Seriously? Where else would you put them, my house passed inspection with them in the walls.

Not trying to start an argument, just trying to learn for the next house.

Rancher

[markts30]

They can be placed in the wall but should be accessable for service/replacement... (access panel...)

[srdenny]

In some jurisdictions, a code approved arrestor can be buried if it's manufacturer's installation instructions say it can.

[Redwood]

They can be placed in the wall but should be accessable for service/replacement... (access panel...)

That is what I would do!