I would avoid KJW if possible. I have had many problems with them and herd quite a few horror stories about them. One being the chipping of paint and chrome finishes, which would make your pretty silver look pretty bad. The note on the bottom of your link to the gun is not very promising as well.
"NOTE: Safety lever may cause gas discharge and shoot if the gun is chambered, always point the muzzle in a safe direction."
The TM Hi-Capa 5.1 would be a great gun. There are plenty of after market parts for it including a metal piston head from guarder which should fix the o-ring problem when firing propane. I own one myself and would recommend it to anyone.
http://www.airsoftcanada.com/gallery...php?i=3541&c=4
As for Western Arms they would also makes a fantastic choices and can fire propane very reliably with just a little upgrade from Airsoft Innovation.
http://www.airsoft-innovations.com/i...ducts&id=AI-03