Re: Mesa Boogie F-30
It's a good amp, and a DEFINITE upgrade IMO. It is what evolved into the Express 5:25 (which then evolved in the Express Plus 5:25, the current offering). I had the F50 head, which is the 50 watt version in that series. I only got the 50 because it was a blowout deal that I couldn't pass up; otherwise, I would have got the 30 because it's a better sounding amp IMO. The F30 and F50 are pretty much like the Express and Express Plus 5:25 and 5:50, but without as many useful features. They don't have the clean boost, foot switchable 5-band e.q., variable power modes, or a few other cool things. I now have the current evolution of the amp (the decked out Express Plus 5:25 mentioned earlier).
The F30 is an inherently "better" (IMO) sounding and significantly more versatile amp than your Marshall, in terms of tone and malleability. I'd take one over that Marshall without even thinking about it. That said, I gravitate toward lower wattage, dual-EL-84 or 6V6 amps most of the time. I like the way they respond, and I'm used to it, so I would of course tend to favor the F30, even if it didn't have all the extreme tonal versatility.