Disclaimer: I like Cyclades products. They Just Worktm
Yesterday and today I got to have a fiddle with the new AlterPath ACS product, and they're very special. I'd previously used the TS product a few years ago, and been quite happy with them, especially when having to use Digi's cheap imitation, that didn't Just Worktm.
I got LDAP authentication for individual ports working reasonably painlessly, and for good measure, then enabled local LDAP authentication to the terminal server itself, with similar ease.
The web GUI is a bit sluggish, but was still useable.
The userspace environment on the box was a bit stripped out for my liking, but still useable. A non-BusyBox vi would go a long way, as would iproute, but other than that, I really can't complain.