mad_jock, NIS/NIS+ were dropped in favour of the more formal LDAP technology of which openldap was a nice easy replacement. ADS is just a glorified LDAP which if you are already using because you have Windoze users then it makes sense to stick your *nix users on it too. It just simplifies things. NIS/NIS+ concepts still pervade in most *nixs today (e.g. nsswitch.conf) and I doubt will ever go away.
The only issues I had with my setup described previously is your typical Windoze admin was not able to grasp these advance concepts easily and they constantly kept breaking stuff because there was no technet article for them to follow by rote which put them in the dangerous situation of having to think for themselves. Otherwise it worked very well.
Microsoft have really lifted their game on network security and in my opinion they are finally doing things right - they had too. This is why they say that the biggest changes with Win8x were under the hood. But that still doesn't make me a fan of "the Microsoft way".