My multi-year experience with modernized M14s and modern chassis stock systems gives me a different perspective than most.
If you want to scope your M14/M1A and shoot with optics most, if not all of the time, you are needlessly handicapping yourself if you do not utilize one of the proven modern chassis stock systems.
On the other hand, if you desire to do most if not all of your shooting with the awesome iron sights on the M14/M1A you are needlessly handicapping yourself if you utilize a non-traditional stock.
I have found one variant of a modern chassis stock system that does not handicap the iron shooter or the optic shooter, and that is the SAGE EBR with the Magpul PRS2 butt stock.
Hope that helps.