As far as spares, I've got an extra primer pin and spring, and decapping pin.But in approximately 10,000 rounds, haven't had to replace them. Others have commented about breaking the powder chain, but I haven't had that happen either.The loadmastervideo forum mentioned several times is a wealth of information. Can't say enough about the mods from Mikes Reloading. I have the billet turret, stabilizer and shake brake. Since i haven't had any problems with the priming system, am using the stock parts. You do need to do a good cleaning every few thousand rounds to clear out any debris on and under the priming pin.
Will second the recommendation to keep parts properly lubed, especially the bottom of the case slider. After proper cleaning and lube, the ram will fall down by itself, so don't let go of the handle.