I stopped my highly available DRBD server setup today. The way I had it setup wasn't optimal, but it was a worthwhile effort and experiment. I had my system setup as a primary / secondary, which I don't believe is as optimal as a primary / primary setup. I found the delay time between the transfer to be slow, and recovery to be problematic with my configuration. Perhaps I set it up wrong, but it wasn't worth having two machines up 24/7.
As an alternative, I plan to use FreeNAS, which I believe to be incredibly stable due to the fact that it uses FreeBSD and compact flash as its OS storage mechanism.
UPDATE: I installed the latest version of FreeNAS today and I'm really impressed with the improvements over just the last beta version (I think they may have even fixed the NFS bug). Its a terrific product, if you haven't tried it - download it today! Another thing I noticed in the newer version of FreeNAS is that the console sets up the LAN ip to have an IPv6 address - I gotta try it out. I've been meaning to start using IPv6 but hadn't had a good excuse yet.