The lowest group mission, Grounding the Drakes, is worth 22 crystals.
The mobs are DB to lvl's 57, but they are quite tough. We went in (as a guid) without any CC and got our a[b][/b]sses handed to us. One add showed up, my heal didn't land (intertuppted), then group wipe.
The drakes gate, CH, mez, charm, probably fear, and are all around nasty.
I've done mission in the 60's and they went a lot smoother.
If you've got the CC in your group I'd go ahead and try it, worse that's gonna happen is you'll wipe and need a rez