Wohoo! Now I'm also a proud owner of a Super Twin!
I was lucky enough to find a "used" one in very good shape. No signs of use whatsoever, hardly even dirt on the wheels... It arrived a couple of days ago and tested it yesterday. (Or well, I had to test it on bedroom levels when it arrived on wednesday, just to be sure the drivers hadn't been removed behind the silver grille.

) I knew the cab was very lightweight, but this felt for sure way lighter than I had expected. Very easy to carry in one hand with one of the side handles. I tried to pull the cab behind me taking advantage of the wheels also, but obviously I was too tall for it being comfortable. Measuring 176cm (5'9"), I could hardly be considered tall though. I had to bow my back and knees a little when pulling it, in order to prevent it from tilting back into standing position, which it otherwise did. It's more convenient to carry the thing instead.
@Alex: In future versions of the cab, I'd suggest replacing the handle on top with a telescopic one, like what's used in most trolley bags today. That would be more comfortable and useful. As it is now, the wheels on the back don't really make much sense. I rather carry the cab instead of pulling it behind me.
Anyway... Yesterday I took the cab to our rehearsal room to test it with my recently acquired Markbass F1. The basses I used were my Fender Jazz Bass ('62 IIRC) reissue strung BEAD (roundwounds), and my new Godin A4 fretless in standard tuning (TI flats). I quickly noticed the F1+ST combination will be loud enough for any occasion. I didn't have to turn the master higher than to 9 or 10 o'clock before it was way too loud for this room (25m² = 270sq feet). The windows started rattling with the master at approx. 9 o'clock, and I wasn't too aggressive on the gain knob either... For testing purposes, I pulled the master further up towards 12 o'clock for a while, and it worked just fine. However, I need to test this at a gig or in a larger room before really being able to evaluate the capabilities of the cab and amp at higher volumes. You can't really do it when the volume gets so overwhelming as in this tiny rehearsal room. It all looks and feels very promising though. This combination definitely feels louder and more aggressive than my old Yamaha rig, also 500W as the F1, but put into six 10" speakers instead.
With everything set flat, the sound is quite midrangey compared to the sound I'm used to with my old amp, and perhaps a bit harsh in comparison. I don't really know how broken-in the drivers are though, so the sound might get a bit smoother over time. In the meantime, a bit of eq should solve the issue, if there even is one. I need to test this with the whole band to be able to tell. But first up are the christmas holidays so that has to wait a week or two.. Regarding the sound, I've been looking for a more aggressive tone for some songs, and I easily get that with this setup. Strong enough mids are also needed to avoid getting lost in the mix, as we know, so I'm positive I'll be happy with this new setup.
On a side note, I can't but love what's happened over the last decade with bass equipment. The powerful and ridiculously lightweight digital amps that fit in the gigbag's side pouch, as the F1, and really lightweight and small cabinets with extremely capable drivers, as the Barefaced ones. I want to send a warm Thank You to all who has contributed to this development!
