I 'm in the same boat. Been looking at some softer tires for better traction, but have been concerned with wear. I was at the St. Joe Nat'l Enduro here in Missouri, and looked at a fellows S12's after the race. I was amazed at the condition of the tires. No chunking at all!!!! and St. Joe has alot of nasty rocks. This alone sold me on which tires too get for my 220.
Dunlop's for me baby! K490 in the front and K695 in the rear. Was going to go to 739's but found replacements too cheap, I couldn't pass them up. The K's gave birth to the 739's later anyway, so it's like the same tires. TP runs anywhere from 5 to 14 depending on the conditions. If you don't think TP isn't important go out and try and ride in semi-muddy conditions with 12psi. After you stop sliding around you'll stop and let out some air.