There's already quite a few threads on here in regards to their ammunition. They're about the only ones around who offer trigger work for the FSN, not to mention a 5.7x28mm case gauge.
On the ammunition side, you'll get varying opinions on that matter. Obviously since it's not factory FN ammunition, if you have an issue, FN, will most likely void your warranty..
With that being said, I've shot quite a bit of their ammunition, and documented a lot of it as non-scientific testing. I haven't had a single issue. I really like their Protector loading, along with the S4M, and their T6 round.