I've tried all of them, and ended up sticking with the USI Tripple threat's. Not sure how they would work on the Yammi, but they work awesome on the Doo's. I really liked the Mods on the Rev, but not quite as much on the XP. JMO! I have a set of Simmons sitting in the garage waiting to go...
99% of the people complaining about them don't own one. I guarentee there stronger than the Revs. Mine ghost rode into a tree, and took 1/4" out of the tree, and all it did was bend the a-arm slightly. Still rode it the rest of the year. My buddy slammed into a 6" fence post, and stopped him...
I tried a boosted Apex, and a TM1000, and still ride a stock sled. Both were quite the addrenaline rush, but just not for the kind of riding I enjoy. We took 1 of my buddies on a deep snow day last year, in the tight trees, and he couldn't stay with us. On the straight up hills, he smoked us...