I've never really liked the idea of splitting the player base right from the start into different rule set servers.
I've always loved that idea. It's probably the best idea ever to surface from an MMO.
Alternate ruleset servers can get me to play a game I would have previously ignored. Iron man, pvp, pve, rp-pvp, rvr, perma-death, ffa/team/deity pvp, progression etc. And there's always petitions for a classic ruleset servers. For UO, people want pre-Trammel, for EverQuest it's pre-Luclin or PoK, and SWG it's pre-NGE. I've even seen WoW players ask for a classic server, and they've only had one expansion.