It doesn't hurt anything. There's many many threads on various forums about it. I'd stay away from any gun company that says it will void their warranty. They put out inferior products and weisel out of their warranties this way. Any quality firearm shouldn't have an issue.
I've heard some people complain about arsenal triggers. If you don't like yours and end up wanting something different, look at the ALG AKT. I like it better than my norinco (and people love chinese triggers).
I love AKs as much as I do ARs. I've always wanted an arsenal like the one you have. She's a beaut! I've owned a lot in the past, but my current is a mak 90.