I've talked to Jim about them and they seem pretty sound.
They just require a very little bit more grinding than the 4.7's do on the shift rail.
There is also a thread on PBB about them. http://www.pirate4x4.com/forum/showthread.php?t=554130

If you really want to know more, call Jim.

that was a thread i started a while back, and he is right call Jim.  i posted my answers up in the thread and they sound like a good gearset to me.  the only reason i dont have them in my truck right now is because i dont have any more money, but when i get enough i plan on purchasing them.