Holy crap... there are so many small amps, any of which would be a good replacement for the SWR if all you need is less weight and more volume. I've been through a pile of them, both on gigs and at music stores. The best sounding amp I ever had was (actually is) a Genz Benz GBE400, so when I play through any new amp that's kind of the tone I am looking for.
Mesa 800, 800+, WD800, Walkabout - all warmish to warm depending the model. Good features sets and EQ. Of that group I like the 800+ the most, but the tone is a little dark for my taste.
Markbass - Maybe I should give one a shot again someday, but not an amp I can easily get a sound out of. The F500 was my favourite of the group, but it wasn't good enough to commit to. Someone earlier said something about "hitting you in the face, and not in the chest" - that's how I feel about Markbass.
Traynor - not bad for the money, but not the sound I want. Decent enough power for sure.
Genz Benz Shuttle 9.2 - Close, very close... but not the tone I was after. Plenty loud, but didn't feel like there was substance behind the volume. Good EQ.
Genz Benz Streamliner 900 - even closer and better than the Shuttle, but I could never quite get what I wanted out of the EQ. This amp - paired with a Traynor TC115 cabinet (which weighs a ton) did a terrific job of mimicking a 1964 Ampeg B-15N. I would have kept that rig if I had extra room in my basement. But I don't.
Ampeg - I have tried so hard to like Ampeg... 2 types of B-15, SVT, V4B... It's just not for me. So, I wasn't surprised when I plugged in a PF350 and was completely underwhelmed. I hear folks raving about Ampeg stuff all the time. I don't get it.
Aguilar - Like Ampeg... I want to like it, but I don't.
Orange - Nope. Not a fan of the sound of the bigger stuff, even less so of the class D offerings. I wanted very badly to like the Terror, but I couldn't. Just not my cup of tea.
Tecamp - Almost... but no
Gallien Krueger MB800 - Love it. For whatever reason, the control set fits my preferences perfectly. The EQ points are just where I want them, and the mid-scoop and presence switches function exactly as they were intended to. Loads of volume. MB500 and MB200 are also excellent. To me, it sounds like the preamp in the MB500 is a little different than the MB200 and MB800.
Genzler Magellan 800 - Another close call. A very good sounding amp, but I already had the MB800. The MB800 has a 4 band EQ, the Magellan had a 3 band EQ. Experience tells me that I like 4 bad better than 3. Decision made.
TC Electronics - Hells to the naw.
Bergantino B|Amp - After gigging the MB800 for 4 or 5 years, I decided to treat myself to an upgrade and bought a B|Amp. In my experience, the most transparent bass head in existence. Excellent control set - so many presets and functions. In fact for me, too many. In your basement, there is lots of time to time to fiddle with presets. On a gig, not so much. After about a year, I found myself not needing all the functionality, and while I appreciated the honesty of the B|Amp, I preferred the attitude of my GK MB800. On a side note... If I were to do the Bergantino thing again, I would do the Forte. No digital controls to work with, and I think the Forte sounds a little less compressed than the B|Amp. There is also a Forte HP, it's louder than the Forte, but has some noise issues. It has a nasty pop when turned on and off, and hisses a bit.
Gallien Krueger Legacy 800 - This amp came out not long after I switched back to the MB800 from the B|Amp. Brought it home for a spin, and was thoroughly surprised that it was a clear step ahead of the MB800. It reminded me of the MB800 (and the RB800), but slightly rounder tone, and more authority. Again, the EQ controls and tone switching are eminently useful. I run it with a Bergantino HG410 cab. It's an amazing combo that I can make work practically anywhere.
Some day I will try a Quilter - I imagine that I will probably like the tone, but the minimal control set will leave me wanting. For me that is the secret sauce of the GK stuff... It has exactly the control functionality I need on a gig.
Anyways just my opinion on the matter. My ear, my gear. YMMV. There is certainly no lack of options.
TL;DR version...
I like the GK Legacy 800.