I've never used either , but from what I have seen and heard the johnny joints are awesome and the revolvers are junk.
I'm sure with the revolvers it would flex better and look impressive on a ramp , but having extreme flex is not everything. If you have to use some type of shackle like a revolver or a buggy leaf setup to get enough flex out of your springs then you probably need to just get some better springs.
The johnny joints are not gonna give you a lot more flex , but they will help some. The good thing about the johnny joints is that they will keep your springs from twisting as they flex, which takes a lot of stress off of the main leaf.
I would much rather have a good solid suspension setup (such as marlin's) over a super flexy ramp queen that does not work good on the trail . My