I play milsim paintball with authentic gear. You can't get dirtier than paintball, unless you play in a mudpit. Airsoft is a much "cleaner" game comparatively. You don't get clown colors on your gear. I switched from paintball because - among other reasons - mud gives your kit character while paint is just....hard to wash off. I can't speak for everyone, personally I wouldn't be able to enjoy myself if I had to be constantly worrying about whether my gear works or whether the straps will break if I do this or that.
I'm not writing off all repro gear of course, if there's a setup that's fairly tough and robust then its not a bad deal. Since we don't really use it on a daily basis. But I've been in situations where I go on a wire obstacle course in the day, and have to patch my webbing with electrical tape at night to prepare for the next day - and this is on "authentic" issued gear. By the end of boot camp I was ready to be rekitted with a new webbing. They better issue me new shit when I go back to my country for reserve training.
Good stuff there Farmboy. Sure they're slightly over 200 bucks, but I'm sure we can forego a few bags of BBs
If we go along with MadMorbius, raw materials for scratch builds anyone?
http://www.diytactical.com/main/