FWIW, I've been able to A/B the 2150 and Classic Reissue and they are both completely insane. For example, I'll play any old head as normal, then reamp it through one of these power amps and it instantly makes them sound twice as enormous. Everything you've read about them is pretty much spot on...the 2150 is a bit tighter and rawer, with a bit more aggression. The Classic colors the tone with a bit more warmth and sounds more 3D. Still plenty tight though if pairing with a tight-ish preamp.
Honestly I would have a hard time choosing if I had to pick one. I probably play the 2150 more, but having arguably the nicest EL34 power section in existence is insane to play around with when that flavor is desired. I'd imagine you can score a 2150 for cheaper, though everything is obviously ridiculous right now. I paid $1800 for mine a couple years ago and had the seller ship directly to Fryette for a checkup. The classic was $4k new, but LA Vintage Gear was able to do PPG and save me the tax. Totally worth $4k+ man, just bank on selling that Purple Marshall of yours in the classifieds and go for it!