I stumbled upon a FAQ page about springs and coilovers, and the writer is saying that an negative aspect of coilovers is that there are regular rebuild cycles instead of a permanent installation. Is this true, and to which coilovers? How often does one send out coilovers for rebuild?

Here is the link to the page: http://forums.nasioc.com/forums/showthread.php?t=911257

What are the difference between sleeved coilovers and "true" full coilovers? I've read about them, but still don't quite know the difference (pictures would be nice). From what I know, sleeved coilovers are shocks with seperate springs that you need to buy to fit over the shocks; and true coilovers come as a set.