Wow. I really feel like someone spiked my coffee with acid when I read these threads

. I've owned a nice little collection of GK gear, including an MB210 combo with an added MB15, a Neo 212 combo (discontinued) which had a 1001RB head that I added an additional Neo 212 to, a Backline 600 and yeah... I've mixed and matched a lot of that list. I also owned a Bassman 250 watt 1X15 and I kid you not, it blew away all the above. I'm still not sure what that's all about, and why my experience differs so much for others here, but I imagine it comes down to 1 of 3 things. 1. I play in bands much louder than many of the people who post on talkbass? 2. At the time I owned those amps I was playing mostly a Bongo and a Stingray, and GK has a rough time handling what they can dish out? 3. I have the sheiittiest luck in the world when it comes to purchasing anything GK, or Fender for that matter. I do own 3 Fender basses though that I love.
FWIW, I've played probably over 2000 gigs in my life, and with different backlines and studios played through hundreds of different bass amps. I love the 80s GK stuff. Aside from that, I'd take just about any amp these days over any of the newer things GK puts out. Every GK amp I've owned sounds great, to a certain point in volume, and that certain point has always been way too low for me to cut through in the bands I was playing with. Even when I was using 1001 4X12 setup. As soon as the amps started moving any air, they also started farting and rattling. And I'm not an idiot... I set my basses pretty much flat, sometimes even cutting the highs and lows, and I always start with the EQ flat on my amps. I tweaked endlessly to get a gutsy ballsy sound that cut with all my GK gear, and unless I was in an incredibly low volume situation, it was impossible to do. I always had to settle for the loudest sound I could get that would cut, and that was it. No tone shaping, no getting what I really wanted. At least not without farts and rattles.
What I eventually settled on after going through lots and lots of amps and combos, is a Carvin BX500 (one of the most versatile and tweakable heads I've ever played through), and a Bergantino NV610. I still have a GK Neo 212 that I use with the Carvin head for smaller gigs, and it does sound awesome, but for nothing more than a small bar. Since I love the Carvin head so much I recently picked up an MB110 combo with an extension 15 - and even though that combo has less wattage and speakers than the GK MB setup I had, it destroys it in tone, volume, and versatility. It's lighter and smaller, too.
Not looking to argue with all the GK love here, just sharing my experience. And RE the Rumble. Never played through one of those other than in a store, but the above mentioned Bassman was uncharacteristically loud for an amp it's size, and put out some serious thump without rattling or breaking up. I sold it to a friend cuz I had too many amps in the house, and have since regretted it. My goals in amplification have always been to get as loud as possible with the ability to tweak and dial in the tone I desire at loud volumes - and to get as small and light a setup as possible. The above has been my experience (including the purchase of the NV610 which is amazingly small and light for a 610 cab), and what I've settled on. I have no amp gas whatsoever any longer.