Yeah, the PDC for some strange reason has a stop order on WGC, and RWA has none in stock but may get some more in.
G&P's is basically just a replacement hopup unit, done in metal, versus the PDC where it is physically built more as an upgrade. It seals better on the gearbox, and the adjustment is very nice as well. Plus is designed a whole lot better, so if you accidentally pull to hard on the barrel when removing it, it won't snap off a tab or anything.
This being said the stock hopup unit is fine, the bucking and rubber is absolute crap. I personally have had the stock CA one, then installed a madbull one and had still pitiful range, then installed a proper systema rubber with TM bucking and it worked excellently.
Also, you don't necessarilly need to get a specific kit for airsoft in Canada. Generally speaking for milsim events, you'll need some matching camouflage, but whatever looks good to you generally fits into these sort of events.
This being said, all black and a pea green helmet with a Glock and you can go as GEK Kobra
(Only CT/HRU to train with firing AUGs out of helicopters)