I have Bill Mohr's spring, which I purchased from Cannondale for my RTX SE. Overall, my experience has been positive. The stock center shock spring would bottom so easily. It is much better now. The sled was wheelie monster when I first put the spring in(Limiter straps were all the way loose, transfer blocks on 1, springs on 1). I've dialed it back some for trail riding. Overall, I'm happy with my purchase.
My Dad has the Raptor triple rate in in LTX SE. It seems to be more plush than mine, but that could be the difference been the 137 and 129 skids.