I run the longer shocks and tower with vrp valve pistons, chrome shafts and machined internals. It has really helped keep the back end stable on a very bumpy loose track. If your track is bumpy I would say it's worth it. For smooth Clay I wouldn't bother.

I run with the orings but wouldn't say it's necessary. I have never run without them to see how close it is to having the drive shaft pop out from the center outdrives.