I replaced ours this year with ISC DHCP and ISC Bind. You'll want to make sure you properly handle the "_" zones that Windows AD servers use. We just use IP based auth to allow them (Domain Member Servers) to make their dynamic updates into those zones. We use dynamic updates throughout and have written simple commmand line tools that allow us to add/del entries.

Seems to be much more reliable/predictable than Windows AD stuff (we run ours on Linux of course).