Thanks @knedlsepp @TLATER @jonringer and @rgoulter for all your thoughts 
I give the talk next Tuesday, and will continue to keep an eye on the answers here to incorporate into what I say, thanks again!
@rgoulter thanks, yes, for me I started with Nix on macOS, then took the plunge and I do agree it is a nicer Nix experience on NixOS.
@jonringer 
nice to hear further confirmation that on NixOS “well, it works for me…” is history 
@TLATER thanks. Just yesterday I was looking at Add /bin/bash to avoid unnecessary pain 
@knedlsepp for sure, I really relate to your comment about no longer having the urge to do OS re-installs.