I only have the damage upgrades left, but I'm finally wielding and feeling its power. I don't want to go back.
After finally doing hard VoG and getting a vex and a fatebringer, I spent the day switching back and forth with them... for PvE, they're both awesome. The Vex actually made me put away my Icebreaker for a while and mess around with some of my shotguns. I think FBringer will make me put away WoC for a while. I'm a fan.
Any story or strike missions,
with many throw away enemies, like thrall or dregs, Fatebringer is a god send, and makes for some epic one shot multi kill explosions in blue arc damage.
Be ready to run with in it the next nightfall with arc burn, I find myself still getting most kills if no one else in the party has fatebringer but me.
Ran VoG again yesterday... All I got was a damn chest
Your best move is to do hard mode every week with multiple characters, and if you are only looking for fatebringer, focus on Templar fight only.
If you want to keep GAF friends on the other hand, be willing to do the whole thing. Team player, and all.
If you are looking for secondary, and heavy weapons from VoG, make sure you do normal mode before hard, as you get 2 chances at them like that.