Hi,
I am enjoying Rage much, I think it's good. However I have reached a... "quest giver" in the bar in Wellspring who's got a defibrilator Upgrade for me if I give him 20 feltrite crystals. Is it worth it? I save often and in the 21 or so hours I've spend on the game I've relied on the defibrilator 4 or 5 times. I worry that there might be other people who want them crystals in return for good gear. So to those who have completed the game, are there other points in the game where you can exchange crystals for good gear/items/weapons or other stuff? As opposed to just selling them at a vendor.

Yeah, should I save the crystals for something else later in the campaign? Please help me out!

Yes the crytals in this game do nothing for you besides the upgrade & loot... In the full game i bet they are very useful... plus u get a bunch later.

my first playthrough i didnt even find that mission from the dude at the bar and i was fine

the second time i played through i did that mission, got the upgrade, but didnt notice any difference or what it even did for me

I went for it, and used/needed it in the next mission.

It is $500 worth of feltrite though so if you're short on money don't do it. If you have plenty of money as it is go for it, it is a little useful. Lowers the recharge time slightly.