I never said Dart sounds like SET. In fact, I get tired of folks trying to say tube sounds like ss or vice versa. They are just different and have different traits, SETs in particular. I will say the Dart is the best SS implementation I've heard- and I have had the First Watt SIT-1s in my room.
Look at Stereophile measurements of a Cary 805 which is the poster child of distorted SET bass from the 90s- its very difficult to get an output transformer that low single-ended. This is what you want to avoid and why measurements are more important with SET than any other type of amplifier. If you read Lamm's measurements, you see how spectacular his transformers are. Almost flat to 20hz. Wyetech would be another- check out the Soundstage archives for SET reviews. I heard Lamm ML3s last weekend and it was one of the best systems I've ever heard- on Wilson X2.2s, not normally my favorite speaker. I've also owned a Almarro 318B and it was one of the most distorted amps I've heard. Sophia Electric makes some good gear, but my 845s blew up on me and I had to return them- it was the first pair and I don't think they were ready for prime time. I probably should have bought his old version with wood panels and called it a day as the Sophias had tremendous drive. I also borrowed Dehavillands- but quite frankly, despite good sound I just couldn't get over the garage built factor. They look even more awful in person.
I had a pair of 15w Quad II classics (very, very good amps properly retubed) that had considerable more bass/drive than 25 watts 845 SET. Weird, eh? It just depends on your room I guess.
I'm going to get to hear the Shindo GM70s in two weeks (I hope). I'd also say I like KR Audio gear, but it doesn't sound like traditional SET (ss input, SET output) and freaks people out sometimes. The KR 350i is the one amp I might purchase used to try out, but they are rare in the US. I've already had 15, so what's one more amp?