I've also been looking at PowerBroker Identity Services from BeyondTrust. It is where Likewise ended up after a series of acquisitions. It looks like I'm going to have to be building a virtual network and trying some of this.
I've used this in multiple companies, from an airline in America to an oil exploration company.
Works like a champ, it's built on Winbind, but now has actual support versus calling RedHat and hoping for the best.
Did you use PBIS Open or the paid version? The paid version is significantly more than I can afford at about $1,600 per server instance.