the main issue i see linking Materia to other datacentres in going to be the latency.

oceanic players have gotten used to playing at high (~200ms) latency becuase they're wasnt an option for otherwise.

opening access to other DCs wont realistically solve many issues. non-materia players wont come over to experience higher latency, and most likely non-materia player will prefer players from their own data centres to avoid latency based issues.

as far as alliance raids, i feel materia has mostly settled upon using partyfinder to make groups for these, often you'll see party finders up for raids and these will fill quickly when compared to queing it as a roullette.

speaking from personal experience, myself and many of the people i play with dont que for alliance raid in duty finder soley because we're all sick of crystal tower