If the group you are playing with (whether its friends or df or whathaveyou) then hey, go for it.

That said, Jobs outclass the classes in every way, even with more limited cross-class options. The only one I've heard of that could be viable was MRD, and even then if I'm correct WAR as it is now outshines it anyways (I think it was back during just 2.0 when it did, and by 2.1 it stopped outside maybe PvP. I honestly don't know.)