I've never run them but I've noticed they have fallen out of favor with the Americans due to unstable body roll and wheel hop problems climbing rocks and hard uneven surfaces... its all cause by the drop piece as it folds out
If you look in superior's web site you'll notice the pics of the trucks showing them off are also using a track bar this would definitly help with the wheel hop issue coused by the suspension loading and unloading.... I looked at running them along with my front hinge setup but the unloading of the drop piece is the big issue when doing hard steep climbs, thats why I went with just a side hinged shackle.... still tempted to try a version just couse of the big drop you get with drop shackles
I've also noticed they fall in the gray area in the cert rules, no direct commets either way

(same deal as my hing setup

) this means getting them certified will depend on the certifiers discretion

why I made mine overkill
Cheers Reece