I love my 716. Never had any problems with it even shooting crappy ammo. There has been discussion of generation 1 and 2, but Sig said there is no such thing as a gen.2 716." there have been some changes through time but nothing that would warrant a gen.2 title." There is a gen.1 and 2 in the 516, but not the 716. At least that's what they told me. He could be smokin crack though. It's really a great rifle. I put the UBR on mine and with a 2 1/2" buffer, I was able to keep the flat spring. You can't change the hand-guard, but there's no need to. It's got a nice one. I switched to the RRA two stage trigger and it's a lot smoother. Stock is a little gritty. Running a Leupold Mark AR 3-9 I'm taking out soda cans at 400 yds. with cheap lead tip ammo. For some reason their bolt uses gas rings that do not serve a purpose according to Sig. Maybe a type of bearing or guide? I went with a McFarland one piece just to make sure it would never break. Sig said I could probably remove them and it wouldn't matter, I'd rather not experiment with that on my rifle.
I've been on a search trying to find out if there is a 20" barrel I could put on it, but nobody knows. Not even Sig. They don't have any information on any aftermarket parts for it, so let the forums be your friend.
Congrats on your new 716. Enjoy.