The notarization will help you waive the long interval between G1 and G2 or G test. Since you had 2 years driving, you are eligible to take G road test right after you pass G1 written test.
However, it doesn't help in insurance. Local insurance company will agree with your China records but they won't calculate them because they don't have any way to verify the records. Although you had driver license, it doesn't mean you had good driving records in China. When I bought auto insurance the fist time, the broker said if I could provide notarized "insurance records" in China (not the driver license), he MIGHT credit me $20 (When he said that, he was not so serious). I don't think the notarization, postage and transportaion could be covered by $20 (RMB100-RMB150), not mentioned that I had to bother friends. So I gave it up.