Moon, that is a really nice rig. The more I play the Musicman, the less I want to part with it. There aren't many amps you can legitimately play bass through that have a good guitar tone too. I'm always surprised how much bite that 15" cabinet has with a guitar.
I had a young metal drop-B tuning dude in here last week buying a Fender Ultimate Chorus 2x12. It's not a very loud amp so he really liked it when we hooked his fancy Digitech pedal up to both the Fender and the Musicman and got them balanced. As he was about to leave to think about the Musicman he said, 'what's the deal with those?' pointing at my SWR Workingman 15 bass combos. We hooked one of those up and it was even more of what he was looking for. The pedal is doing almost all the tone, so all he was really looking for guitar-friendly powered monitors. So, much to my surprise, he ended up taking the Fender and one of my SWRs for the low-end support - mostly because it was about half the price and half the size of the Musicman (but not any lighter). He ended up with what is an unconventional set-up for sure, but the sound is FEROCIOUS and loud enough to compete with a drummer who's an absolute basher. The Fender screams and the SWR moves the hair on your legs from 10ft. away - without it becoming a big muddy mess.
I was genuinely impressed with the tone for that style of music, it was powerful, but still really responsive well-defined. Half the time when I hear young dudes playing that kind of music they might as well be using a chainsaw. I can see their hands moving 4 frets, but it's hard to discern the audible difference between the washed out buzzing F power chord and the washed out buzzing A power chord. This rig is the antithesis of all that. The 15" really suits the super low drop-B tuning.
Right now I'm thinking I might keep the other SWR combo and keep the Musicman cabinet for an extension speaker. Although I'm primarily a guitar player, I still get last minute calls to be a fill-in bass player from time to time. Besides, it will be a lot less hassle shipping the head out of here than the stack.
I want to keep enough stuff so that when we're finished with the building I still have a complete backline, drums, and PA set-up so a band could walk in (motorcycle in, dog-sled in, parachute in, whatever) and practice here - so keeping the extension cabinet wouldn't hurt.