Pex for shower only valve install?

I know that valve manufacturers say not to use pex for valve to tub spout supply lines, but what about shower only installations? I'll be using the Delta Multichoice universal rough-in valve if it makes a difference. The valve is also on a sidewall next to the shower head wall as opposed to underneath it.

The reason for using PEX is to the tub spout as it in many cases it creates a back pressure that causes water to rise to the shower arm and make it run or, drip. If you are not using a tub spout this problem is irrelevent. Shower risers can be plumbed in PEX.

Shower only is fine.