The newer shocks are designed to give the same feeling of the older shocks with high performance o rings, only with the stock orings. Most of the team drivers found a better performing shock with the high performance orings in the old shock as they didnt press against the shoch shaft as much. So they replaced with with the high performance orings that are of a slightly different size to have a looser fit on the shock shaft, but still seal just enough. As with many things, it is a compromise. They sacrificed the time between rebulds for better performace.
I havent had any real leakage issues with the new shocks. I do notice my rebound flattens out a bit after a little while, but thats been common with any shock. I found putting a little shock slime on the orings makes for a slightly better seal, which prolongs the time between topping of the shock oil or rebuilding it. Just make sure you use the stock orings, those are what the newer shock was designed around. I've tested MANY different orings, and these are the only orings I'd put in the newer shocks that come in the tc kit.
-Korey