It takes longer to install the Neorest.
But a handy homeowner should be able to do it.
Since you have the studs open, it would be a good time to put the waster supply in the right place.
They spec the water at 11.5" to the left of center.
The supplied shutoff comes with a threaded stop and chrome nipple, so you might think about a drop ear in the wall for the nipple.
Or if you stub out copper, you can add a male adapter to the end of that.
It take me about four hours to install one of these bad boys.