I've never had a CL, but have had a UL, D120 and D60, and currently own a CLX and Sig:X.
I believe the CLX and CL are supposed to be voiced pretty similarly.
CLX has the most gain available, and is probably the tightest though we're splitting hairs there. UL was tightest of all but honestly just didn't speak to me. I think I lacked the right cab for it at the time though.
D120 was like a bulldozer. Mighty and thunderous. Dry, immediate response.
D60 was one of the best modded Marshall sounding amps I've ever played. Van Halen, AiC, etc, while still having a great Marshall style clean (think RHCP circa blood sugar).
Sig:X is like a blend of the D60 and CLX, but a little looser.
The D amps are tops for cleaning up with a volume knob. No amp I've played does better.