I'd go with the CDK700 Alt-Az mount and 28inch scope.
0.05arc sec tracking, no PE, no backlash, high speed, quiet, direct drive, nasmyth focus. I'm sure there are better ones, but at $185k, I'd start with this
http://www.planewave.com/index.php?page=1&id0=0&id=5. Like buying a Merc.