I own a GSG-5SD. They're fun plinkers that have a great "tacticool" appeal!
P.S. -- Be VERY careful with the GSG5-SD model, as unmodified "original" versions are considered NFA firearms. Check on this site:
http://www.americantactical.us/" onclick="window.open(this.href);return false;. Due to an "error" by the BATFE, the larger barrel shroud on the original GSG-5SD renders it an NFA firearm (yes, they retroactively issued the decree). You can enter the serial number to verify if the gun has been fixed. Failing to do so could get you into a world of hurt with the wrong people.
I don't fear guns; I fear voters and politicians that fear guns.