Rampage rolls better than a Fire XC, really?
I find that very, very hard to believe. Rampages are some of the slowest rolling 29er tires I've ever ridden, but they're also some of the best for technical XC riding and they have grip for days.
The Jones ACX's, IMO, blow. I replaced them with Ignitors back in 2005, and in the instances where I've put them back on just to see if they were really as bad as I remembered them, every time they confirmed my previous judgement. I think now I may shave the knobs down on mine and make some lighter weight commuter tires out of them.
Ignitors are great. They're a bit heavy though, so be careful if you're looking for a race tire. Crossmarks make excellent race tires, btw. Incredibly fast rolling. I'm on some Ardents right now- not as grippy as the Rampages, but they roll quite a bit faster.
One tire you probably won't get much use of around here is the Exiwolf. Great tire for dry and dusty areas- sticks like glue to rocks and rolls fast despite being a heavier tire- but the smallest amount of mud clogs the entire tread and renders it useless.
I'm after some Specialized Borough XC's next, for commuting and even some light trails or short track racing.
But my opinion of the Jones ACX, contrary to Vreelands, is that they're not worth your time. Take it FWIW- we all have differing opinions, and there's no one right or wrong answer...