Can I Use this fitting to connect CPVC tubing to a new shower valve
From what I can gather, both fittings are acceptable.  I ended up getting the second style, and after installation, there was a very small leak at the NPT thread.  I could not tighten it, since the CPVC does not rotate relative to the copper.  So, I had to cut the line tighten the fitting and then install a CPVC coupling.  Not a big deal, but had I installed the first type of fitting, I could have loosened the nut, tightened up the NPT joint and then tightened the nut.  Which I suspect is exactly the problem these fittings are meant to address.