Man, that is sweet. I've played with most of the current Eurotrash Wunderguns, and that's the only one that does anything for me. It's still a subgun though. I just hope people who use these things fo a living, well, their bosses, realize that. I'll be all over the civvie version and SBR it.
As far as a piston AR, I could care less. The gas system just doesn't bother me the way it is. Mine works fine. Most of the people I know with them don't have issues. In 2 classes last summer only 1 had any issues, broken cam pin. One class was 2 days in the desert. High winds and plenty of dust, to the point the targets were obscured for a minute or so several times. Only 1 person I know who has been in the military in the past 30 years has any reliability complaints, and he swears his was stamped "Mattel". I have absolute faith in the gas system design as it is and would trust my life on it. A gas piston upper just isn't needed and adds weight. The gas piston on my M14S gets a lot nastier tham my AR, same for my MGs.
The thing I want to see from HK is the re-introduction of the roller lockers. Dirty gas system? No way. Doesn't have one. Don't need it. Nothing to get dirty or foul but the barrel. Personally, I really don't like the G36.
As far as Sigs go, they're OK. Just a fancy Valmet. They handle and shoot nicer than a G36 or AK, but that's about it. If I could get a semi for about the cost of an AR I might. They're supposed to be easy to do barrel swaps on, so an SBR might be nice.
Same goes for an AUG. If it was the same price as an AR, maybe. Wouldn't bother with SBR though. The funny thing is, everybody clamors for the AUG, but the M17S is dead. Why? I like the M17S. It's a little heavier, but I like the little extra weight. It's not hanging way out front where it will get heavy fast, but close in and seems to make it handle a little better for me. Maybe it just makes it feel more substantial, like an M14 over an AR.