So, I hit a GC in Cleveland this weekend, where they had a few Mesa's for me to drool over.
Mark V: I'm kinda glad I didn't get this . It's very nice and all, and a lot of options (figured about 112 combinations), but only three channels? Man, I found a TON of hot sounds on the clean channel, and quite a few in the second channel. I'd want to switch between them so badly, I'd probably have ended up selling it for a TriAxis.
Heartbreaker: One or two decent sounds. Terrible channel/option switching. And no Presence control? No thanks. Not even enough in the Treble to compensate. Definitely a Mark-style preamp, though.
5:25 Express: Pretty fun little guy. Had quite a few options for classic rock guys (my dad would probably like this). The high-gain metal wasn't there, but I doubt they built this for that purpose.
Electradyne: I was the most impressed with this. The channel/option switching was pretty un-engineered, but once dialed in, I liked it. The overdrive was very clear and present, but not too trebly. I can kinda hear the "Brit"-ness of it, as it's a bit more raw and less smooth than the Mark tone.
I suck at reviewing amps, so that's about all I've got . If I had a choice between the four, I'd get an Electradyne head without a second thought.
The Electradyne controls and is voiced somewhat similar to my Budda, although with a different flavor overall. I felt very "at home" on that amp.