I am a Pacific Time Zone player here on EF.
I can only speak from a limited perspective since i tend not to pug, but things seem to slow down around 9pm PST or Midnight server time for things like 5 mans. If you roll Prot spec though I bet you will never have issues finding groups.
That being said there is still plenty to do. Just tonight some pretty balanced PvP skirmishes were happening all over the place. Lots of back and forth. The group i was with was still roaming around til about 11pm my time 2am server time and there was no shortage of targets and in turn no shortage of horde groups trying to rip my head off lol.
When i balance my experiences against what i see happening on other servers i think the pro’s far outweigh the con’s here and it would be worth checking out. That goes for both Horde and Alliance.
Stay Classy EF. Love you all!