Well, word on the street is that getting a group together and grinding mobs 5+ levels higher than you actually yields
more exp/hour than FATEs. Problem is, everyone is so sucked into FATEs now that very few people use the other
method.

Apparently you can get upwards to 1k+ exp/kill at some points. Which can equate to 375k+ exp/hour. Depending
on level, of course, I assume the equivelant of that for say, a level 20, is not quite 375k. Lol. Regardless, it
just depends really. Sometimes FATEs go down so fast you can't make it there in time. I've personally gone
45 minutes trying to reach FATEs in a single sitting, only to get there in time to get exp 10/40 times.

So really, either route is ok. Just depends on what you want to do and if you can get people to party it up!