I have a thread on this stuff in the 1500 forum, basically this stuff can work, but it can also wreck your ride. If your trailer is heavy enough so that it's always riding on the Timbrens, then no problem. If you tow a lighter trailer where the Timbrens don't touch because your suspension isn't squatting enough yet, hitting bumps is painful. I didn't use Timbrens, I bought Sumo Springs but they're the same idea.
If you only pull a heavy trailer, go for it. For me, I pull at least 4 different trailers (they're not all mine) on a regular basis, and I found them to be horrid little bits that came off again the next week. My opinion is now that if you can't make your truck sit correctly with a WDH appropriately tuned, then you need a bugger truck. Again, just my 2 cents.