I use Gentoo on a number of my servers. On my personal server I've been running it for 375 days. Nice and stable. I've done 'emerge -DU system' on it several times as well as a handful of 'emerge -DU world's. The machine delievered 22,000+ emails yesterday no problem. I host ~30 sites, mail, several shell users, DNS, etc etc. 300+ users and no trouble at all.

Gentoo servers are the easiest servers I've ever had to admin. I've admined FreeBSD, Solaris, Debian, Red Hat, and Win(NT/2k/2003) boxes. Gentoo wins my heart with FreeBSD as a close second.

Damon