the durrometer difference between the two is only two little numbers but the compounds themselves are way different. the way they get the different properties is through different types and amounts of oils in the rubber. the slow reezay is softer but it has more oil and different kinds of oils in it than super tacky. it applies mroe to downhill racing than trials on which tires are better for which conditions (ie- roots, dry, hardpack, clay, etc) but for trials, they are booth as sticky.
the creepy crawler tires i have been getting lately have been super tacky. the reason i was told they went with that was because the side knobs tend to fold off the casing with the slow reezay compound. i guess with downhill the cornering knobs are as stressed because the tire is rolling where as in trials we are generally hardly going anywhere when we are using out side knobs and the stress load on the lugs is greater. after a little bit they just start to peel off the casing. you can counter this by trimming them down about 1/3-1/2 of their fresh knob hieght but it's just easier to go with super tacky which has much less tendancy to let knobs rip off.
ok, i hope that made sense... as for my stuff- i run super tacky. i have lost a few knobs in the past on some beat ass tires but it has not really ever been a problem. my tires will often have little stress cracks around the side knobs that creep down around the knob over time. it hasnt been a problem though because by the time they look like trouble the tire is all worn down and the casing is all beat up and it's time for a new tire anyways.