Currently, and as it's been since forever, listed servers are categorized low rate (1~25x), mid rate (26~150x), high rate (151~10000x) and super high rate (>10000x). There's nothing wrong with that, and it's effective, but it would be nice if the servers were also sorted based on mechanics. Renewal, pre-renewal, pre-trans, or even custom.
It that's too much work, tags in the list would be cool. Add in a tiny [Renewal] or [Classic] or [Retro] tag in there, where the PK/RP tags are/were/used to be.