The Sig as mentioned is just a re-branded GSG. I have the GSG. Mine has been a great performer. I have tried just about every brand of ammo through it and it has run great.
Currently I am playing with my GSG. I have run it mostly suppressed since I bought it. The ammo used has been Federal Bulk and Remington Subsonics. I have had no problems with either round. I am now in experiment mode. I have been shooting the gun only suppressed with federal bulk and will not clean it until it jams. I am now at round number 1450 without a jam. Darn thing just keeps on going.
If we weren't all crazy, we would go insane...