I have had 2 Mark IIIs(Purple and Red, loaded simulclass with STR 415s), 1 HRG(Hundred, Reverb, GEQ) 2B combo, 3 2B Coliseums(2 early 1981 versions, one later with a loop mod) and 4 2C+(an upgraded SRG(Sixty), an original HRG, an HRG++ and now a C+ Coliseum).
The 2Bs are very cool with a nice vintage vibe; to me they have the best tone other than the C+. The Mark IIIs are raw but kinda sterile; they don't have the character of the C+ or 2Bs for that matter. At least that was my experience with the 2 I owned.
The C+ will give you almost a 'blanket off the speaker' in comparison to any other Mark...the clarity is that much better. And, that's not to say the other Marks don't have clarity...just a huge jump with the C+. The best part of the C+ experience though is the feel...hard to describe but 'bouncy' is one way to put it; another is that your fingers feel attached to the strings. Very cool and unique only to the C+. It is the king of the Mark amps. I own a C+ Coliseum now but when I look back at the others I owned, the first one was probably the best of all tone wise. The 60w SRG is the lowest priced usually and mine was amazing sounding. No I wouldn't trade my C+ Coli for it but they are great sounding and usually around 2400.
The Mark IV is IMO the closest to the C+ tone and feel of all the Marks...I haven't owned one but did play a used one and was pleasantly surprised in how close it was. Smooth and thick, and compressed just enough. Not quite there but closer than the Mark III for sure.
I haven't played a V but have heard good things. Really, for what most Marks go for used (around 1K, the V for more) they are a great bargain for what you get. Of course that doesn't include the C+, they will range from 2K(an SRG local to me was on Craigslist for 2K recently) all the way up to 7500 for a C+ Coliseum...worth it? I guess to those who will pay that. I did get my Coliseum for far less than what I've been offered for it. But there are less than 100 in the world....
Bang for the buck, if you can find a 2B or III Coliseum that's the way to go. Nothing like these monster power sections, nothing.
