I have a DSL 100 and with the right boost and EQ, it can absolutely hang with my other more expensive amps.
Here's a clip of it I recorded a while back with a GEQ in front used to cut bass and boost everything else, and some post EQ to cut a couple db's of mids at a very wide Q to even it out:
Yep, this is the key to this amp. The amp itself doesn't filter away much low end at the input so on its own it's a bit wooly, but if you boost it, it's killer. And that's exactly what Nuno does with his RAT pedal. If you dial the RAT as a boost the same way you would a tubescreamer or SD-1 (Gain almost but not quite off, Level up high, Tone (or Filter) to taste) it's a surprisingly great boost that cuts out just enough lows to tighten up the amp without going overboard to everything sound anemic or like a half cocked wah.