3 words Freedom of choice ;-)
XRaid with oRA "should" be more ressourcefriendly than CTRA, I never meassured it. I'm sure though that PerfectRaid with oRA is more ressourcefriendly ... or EasyRaid ... or just use pure blizzard raid unit frames with oRA. CTRA is definitly bloated with stuff that not everyone has a use for and there is no easy way to just delete it like a modul (eg emergency monitor ...)
ps: and its not funny btw how long it took the ctmod team to get rid of the freezes that players (not everyone, but many players I know were affected) had when people joined/left the raid or groups got changed -- so alternatives are allways good ... the ctmod team is doing great job, but I think they should begin do recode ctra / ctra bossmods, so its modular...