I like the FN better than the Ruger. IMHO The ergonomics of the Ruger leave a lot to be desired. It's much thinner and flatter than the FN (similar to M&P Shield which I hate). The FN feels and shoots more refined, it eats both proprietary and American Eagle ammo. My Ruger choked on AE ammo. Both have very little discernible recoil, with the Ruger being a tad snappier. Almost everyone I know with the Ruger 5.7 likes it. I will say that currently I have seen a fair amount of 5.7 ammo on the otherwise empty shelves locally.
I'd recommend getting one or the other, to scratch that itch. It's like wanting a Desert Eagle, you won't be satisfied until you own one. If the Ruger was available prior to me purchasing the FN. I would have probably bought the Ruger, considering the lower price point. Both of them sit in the safe until someone asks me about one or the other, then I bring them out.