Hey Les - Any further comments on the Mesa 4x10? That caught my eye as a smaller, lighter, gentler on the 'ole back alternative to a 2x12 or 4x12. It's open, correct?
The back of the cab is truly open, not half-open with a big bottom panel, so the cab is light enough that I can move it around myself without issues. It's also lighter than the pine 2x12 DG30 cab.
But I'm guessing you want to know about the tone...
Normally I'm a 2x12 person, whether in a speaker cab or a combo. I got the 4x10 to have a warmer/sweeter, more vintage tone to go with the Fillmore.
The frequency balance is different from a 2x12, with more of a mid-focus, but so much depends on the amp and speakers - as well as the guitar - that it's hard for me to put my thoughts into words.
Some 4x10s sound a little nasal/constricted/boxy to me. This Boogie cab's very open sounding, with a nice amount of sparkle on top.
With the Fillmore running clean, and a split or single coil neck pickup, the sound is my idea of a perfect clean tone. Doesn't get any better - for me.
Crunch tones sound great. The cab sounds quite good with the other amps as well, most especially the Lone Star (as you might expect, since it's also a Mesa).
The DG30 is a very mid-focused amp that I think matches up best with its own pine 2x12. Surprisingly, the HXDA sounds pretty darn good through the 4x10, especially if I set it up for clean-ish tones.
The Marshall 4x10 is closed. I'm torn. I like my closed 1x12, but I also liked my open 1x12. If I were to stumble on a good example of them, not sure which way to go. I sure liked the cream back 45 watt 10 in my MkV25 combo though.
Edit - Plus, the Mesa is well, ah Mesa.
Here's where my musical peculiarities come in; I'm probably too one-dimensional to express a useful opinion re: a 4x10 closed back cab for other players.
For me, a closed back 4x10 works best with more gain than I use. It's not something I'd buy, but that doesn't mean you shouldn't!