I posted some info on my experience with trials tires on a 2009 KLX250S here:

"Trials tires"
Thumper Tires: All Around Western Desert / Mountain Tires 90%+ Dirt - Page 4 - ADVrider

 

They suck when they pack with sticky mud (lots of clay in Ohio)... at least they did on my Sherpa T. Also not too good if you should lean far enough in a corner to ride off the edge. But the grip when they can... especially on rocks and such. The true trials compound tires have tremendous grip and are quite soft to do so, no bets on how long they'll last with 60-80% paved road use a lot of dual sport bike riders.

 

Yeah, you get lots of different takes on a rear trials tire application. Some of my Utah and Colorado friends love a rear trials tire in many/most areas they ride. However, just about all of them say that if you go into higher elevation when it's wet or different times of the wet season, they can tend to suck. A good deal of sand can make them useless too. In most conditions involving hard, dry terrain...even with loose rocks and such...they tend to shine. It's mud that seems to kill their effectiveness, not so much just moisture. On wet rocks they do a great job...well...as great as wet rocks can get.

 

I'm in BC Canada and recently installed a DOT IRC trials tire. 800 KMS 50/50 and lovin it. 14 psi seems to be a good around pressure. I mostly ride to the bush 50 KMS tear it up in a good mix of everything for 150 KMS then home again. I always wondered why a lot of the top riders ran trials tires on their enduro's and now I know. It tuned my KLX into a tractor. Especially now after installing factory pro jet kit and FMF slipon.

 

I'm running a trials tire on the rear of my KLX, I have been very impressed with the off-road traction.