There are a lot of threads on this topic on various forums. I'll save you hours of reading...
About 85% of guys will say it's the absolute way to go if you have the cash. Less compression, more gain and aggression if you want it. Better cleans...
About 15% of guys still stand by the 101b, particularly because the blue channel is so pleasing in the 101b and the 20th doesn't quite have it.
Not trying to be a dick at all and I know plenty of guys will chime in with great advice, but at the end of this thread, you'll be told that if you have the cash go for the 20th.