Not entirely convinced that making rares OP is a good idea, especially when the easiest way to hoard them is to first own an FC...
I predict forums full of "why can I only get 5 at a time!" threads
Then there is no point to them any longer and they are mere tokens. Something in the game needs to pay big, and rares have great potential since you have to travel with them to get the big payout.
Plus people whine too much. If its not 'I hate engineers' its something else.