Best to keep it as it is, if it works good. Until you're a pro with the firearm and can outline it's deficiencies from a markman's standard, there's no point in "upgrading" mechanism parts.
Btw, nifty paint job. I only have the OD furniture on my subcarbine. Thought about doing what you did, but changed my mind in lieu of keeping the recievers original. I may do a graphic alteration to the handguards and stock, though. Mix in a little brown to break up the monotony.