I had a Mark V, but sold it. I think it's a **** great amp, I won't bash it at all. One of - if not THE - most versatile amp I've ever owned. So, why did I sell it? For a few reasons...
I'd probably never use it live these days with my current bands, so that means I don't need the versatility it offers. It would be for practice jamming and recording.
With that in mind, on Channel 1, I'd be using it primarily for cleans. Well, I have a IIC+ and a JC-120H that can give me solid state sparkle and tube warmth cleans.
On Channel 2, I'd just be using it to dial in some Marshall-esque crunch. Well, I have an '81 Marshall JCM 800 (first year production model) that still has original tubes in it that sounds fantastic. That's all the the Marshall crunch I'd ever want.
On Channel 3, I'd use it exclusively for Mark series high gain stuff. Well, I have a 105 PT IIC+ still loaded with STR 415's. Needless to say, that cover all the Mark high gain sounds I'd ever want.
So with that in mind, I didn't have a use to have $2k tied up in the amp. I thought it sounded great, but since I have other amps that does what I'd use it to do, I could think of many other ways I could spend $2k. For me, it wasn't about the sounds, I thought it sounded great. If I didn't have the other amps, I certainly would have kept it. From a practical perspective, it wasn't worth keeping for me.