Pine, most of the bass players in New York and Brooklyn just use whatever bass amp the venues supply. Regardless of upright or BG. I know several players that play both. One person I know uses a different pickup for thier upright for live shows than recording. I don't know the details but I heard him talk about it. No amp preferences I know of though, in that regard. None of them drag bass amps around the city so don't overthink that part of it too much. Brooklynbass from this forum could maybe speak more to that.
it is not 2 channels but I highly recommend the Orange Terror 500 bass combo. Read the user reviews online. I own one and love it. A shop around here was selling a used one a few months ago. Check one out if you can. Others on this forum may have played the head/cab version of that amp (but the cab is bigger and has different speakers). Happy Face? Pretty sure he liked it. I like the combo for my purposes though. I don't gig but could imagine if I did, this amp would be the perfect blend of power and size for just about anything short of stadiums or arenas, for something so compact.
the Guild Thunderbass amp has 2 channels. One is supposed to be for guitar though. I have the 50 watt version of that. It packs some serious heat but the 2x12 cab is somewhat limiting (but sounds great). There is a cheap one on eBay now. Says its making noises but might just need new tubes. Could possibly be 100 watts which would be some heavy thunder based on my experience w the 50 watt. The 50 watt is plenty loud!