Well jemke, sounds like you've got good taste in rack gear... Here's a pic of mine, btw:
I use the MidiPro to switch between pre's, but the idea is essentially the same... Anyway, I would recommend a Mesa 20/20 over the Marshall for a couple reasons. First is that I a/b'd them when shopping around for a
power amp, and I really believe the Mesa sounds better - atleast for me! Also, the Marshall can ONLY be used in stereo - it needs a load on both outputs at all times, while the Mesa can be used as a one cab mono rig when you want (save hauling an extra cab around for rehearsal and casual jams and really small gigs - oh who am I kidding; I hardly ever bother with the second cab any more...). The Mesa's tubes are exposed in the back to improve air flow and tho' it runs hot, there's plenty of room for circulation - I use a small clip-on fan in the back of the rack that keeps the air moving, and I've never had a problem with over-heating... And the Mesa 20/20 is plenty loud even for good sized indoor gigs if you run two cabs.
