For what it's worth, here's my impression of the amp.....
With regards to "vintage warm sounds", that's not what comes first to mind relative to the gain channel on the Archon. It sort of begs to be played at high gain (and even scooped). I happen to really like the tones of vintage amps and the type of music I play is mainly classic rock / 90s stuff. I really wasn't interested with the Archon until I played it because it seemed like it would be more of a modern gain monster.
But I really like this amp. It really depends on what you're looking for, but I really ended up liking this amp more than anything else in the PRS line. I play in a cover band, and for me, the clean channel with a combination of Fulltone OCD and Exotic BB pedal gives pretty much any classic tone I'd look for. It handles pedals extremely well (actually better than any other PRS amp I have). Oddly though, the creamy tones coming from the lead channel, though not vintage sounding, really sound great in a band environment. I find myself using the lead channel live way more than I'd have expected. It doesn't "cop" vintage tones accurately, but it works out wonderfully. And it gives you the option to get some pretty wonderful modern tones.
In terms of vintage tones in the PRS line of amps, the HX/DA and MDT come top of mind to me. They are both fantastic (I prefer the MDT...but the HX/DA gives you more options...) But if I had to pick one PRS amp, to cover everything from bedroom playing to live band stuff, the Archon would be the one I'd pick.
Although not cheap, it's also not super expensive in the PRS line. If you already have a cab, the cost of the Archon is pretty competitive.
The Archon is sort of a combination of great pedal platform on the clean channel (not exactly a Twin Reverb, but I actually prefer how it handles my pedals). And the lead channel, with the gain dialed back is sort of a Mesa Lonestar...and with the gain dialed up, it's a fire breathing monster.
But if you're really just looking for the warm vintage tones (say something ranging from a JTM45 through a Jube) it's hard to beat an HX/DA or MDT.