I had the DC-2, DC-3, DC-5, & DC-10 all at the same time.
Yeah, I know I have a problem, but it's better than being a Crackhead!
DC-2 - sounds great, but the Contour sucks because it is unadjustable and only works on the distortion channel
DC-3 - great all around amp that is plenty loud enough (especially if you add a Thiele cab). It is hard to find a bad tone in this amp. I have covered anything from the Allman Brothers, to EVH, to ZZ Top with it effortlessly.
DC-5 - did not seem as expressive as the DC-3. I sold it to a Fusion player and he loves it. The tone seems too compressed for my tastes. I tried it as a head & a combo, with many different speaker configs. I just could not bond with this amp.
DC-10 - WOW....Everything that all the other DC's are and it sounds like a Twin Reverb on the Clean channel.
I still have the DC-3 & DC-10, but sold the others.
Also, I had to replace the entire footswitch circuit (LDR's, FET's and 741's) in both the DC-3 & the DC-10. They started acting up, not switching right, switching the wrong things, etc. After the repairs, they work perfectly. I read somewhere that the early ones had too much current being applied to the LDR's, after repairing both of mine, I can believe it.
One last thing, these are so easy to mod, it is not funny. You can do practically anything with these amps and a little know how.