That's great! I was contemplating getting a Mark IIb combo w/extension cab instead of a brank spanking new Mark IV combo, but having heard what Mk IV owners have said about the amps versatility, and it's ability to produce vintage singing leads and modern high-gain, I think the Mark IV would cover my needs.
Basically, I just need an amp with a very sweet, characteristic lead sound with plenty of sustain and dripping with overtones. I mainly compose and perform instrumental guitar music, electronic music and classical music, so I need something versatile, but not synthetic sounding, something organic. My playing is extremely legato, ala Holdsworth, but I also love the santana-style singing lead. The Mark I is a little too vintage for me, and i need something with a little more cleanliness and power.
Anyway, thanks for your help, I think I'm sold on the Mark IV. Oh well, there goes my savings, those things cost £2000+ over here. Maybe I should just get a nice, cheap Cornford stack...