I just got a G20. Used for $700. I wouldn't pay the price for new. I think it's great. The gain is a bit dark and bassy but a Precision Drive in front really helps that out. I also run a 10 band parametric EQ in the loop. Haven't met a small amp that didn't desperately need it. But with the Precision Drive and EQ, into an Eminence DV-77 and Celestion G12H-75 Creamback in parallel it sounds and records great.
I first had a Marshall DSL20CR, then Peavey ValveKing II 20 combo, then Invective MH, then the G20. Each one was an improvement over the previous one, the DSL being the worst. But ultimately, the Vietnamese Marshall and Chinese Peaveys were all muddy, fizzy buzzsaws. Screechy highs, boxy, muddy lows, and wonky mids. The Peaveys have squawky high-mids and the Marshall has this fluffy airy mudrange in the 400-600Hz range. There was nothing I could do with the 10 band parametric EQ to help any of these amps. Cutting the mids on the amp completely and cutting 6 mid frequencies with the EQ and there was still always excessive mids and no definition in the lows and low-mids. In recordings, all you could hear was the harsh screechy noise and the squawky high-mids.
The G20 is SO much more the sound I've been trying to get. Thick low end, note definition in the mids, so much smoother high end. And the best part: no squawky high-mids! I've been redoing my songs with it and comparing the new tracks to the ones recorded with the Invective is like "omg, that was so terrible, wow this is SO much better!"
Yeah, it needs a proper overdrive and some EQ, but don't they all? Out of the 20W tube amps that can be had for under $1000, the G20 is far beyond the overseas junk.
I've never met an IR or cab sim that I would actually use in a finished song. After a week with the TwoNotes in the G20, my opinion hasn't changed. They're fine if you just need to hear it to practice silently, but I've been thru all the factory presets and tweaked out several of my own in the past 6 days, recorded several takes with many of them, and none of it was anything I would keep in a song that I would let anyone hear. I was fixated on high gain tones this whole time, and I just today tried a clean tone thru the IRs and it's distorted thru all of them. Like ugly clipping the high end distorted. Doesn't matter how low the volume is anywhere... I can't figure it out. Oh, well. I didn't have high hopes for the IRs anyway, and I like the amp so much more than the other 3 I've had, and got it for a really good price.