It's got the distinct characteristics of an FN, but there's also a bunch of HK-looking bits in there.
I'm going to have to agree on the whole "looks like an HK" thing. If you can get info on the guts of it, that'd probably more important than physical appearance.
Bush and Arethusa got the RIS handle thing down pat: It's mainly used for CQB or middle-range shooting when you're going to be putting alot of lead in the air, since pulling down the weapon as it kicks up is a breeze with the handle installed. But firing at longer ranges (I'd say +50m) gets cumbersome, and the grip feels a bit awkward since the shake of your wrist while gripping the gun makes it a tad hard to aim. But if you ask me, if you're dealing at those ranges, it's almost always better to have a bipod with you, since the RIS grip makes supporting added weight easier.
As for longer guns having an RIS grip, I'm pretty sure I saw an AUG with the grip on it before. They're out there, but I doubt they're very common.
--Harrm
EDIT: Yep, I was right.