Crunchier and more focused. Channel 1 takes a bit of a hit (less deep) while channel 2 gets a bit more life breathed into it. Channel 3 takes on a more Metallica type vibe with EL34s (crunchberries).... Although oddly for all the mid emphasis EL34s have they make single notes a little more recessive and don't have the same power as they do with 6L6s.
That's my experience with them. I prefer mine with EL34s.
I have a bad habit of assuming most people will use crunch mode on channel 2. When I say that channel 2 gets life breathed into it it's crunch mode I'm talking about.