Love the amp, I just wish I could have it as a 2 channel.
Im a heavy player, in style and in my actual playing. I try to be dynamic with my picking, to be honest I have to be.
For my heavy sound I go for this...
Middle: 4 (6, If I'm wanting some old skool grungey'ness)
Volume: 2/3 (depends on the size of venue and how grumpy the sound guy is at the time
I also had a boss overdrive 2 pedal over the top to give a little added destruction
Now, for my clean it depends on whether its live or studio.
Live = dirty clean,
Same setting as above but I turn off the overdrive pedal and drop my guitar wolume down around 2 or 3. Then its down to my picking. I lightly pick the strings and if I add any fills or licks in here and there, I just pick a little heavier and it adds the extra bite or bring up my guitar volume and pick heavier for a little AC/DC dirtyness to my playing.
Gain: around 3
Guitar volume is around 7. I pretty much use my neck pick up whenever I go clean, for a nice fat sound. Pick ups are pretty high too. Humbucker for the neck with single/double coil tap and hot rails for the bridge pickup. Both Kent Armstrongs.