The existing plating has been fine so far and with it being a dress watch, I do not expect any problems. However, to me and from what it sounds like with your brother, it would probably be worth the extra expense to get more gold put on for peace of mind when meeting with clientele.
I've never been called out on it and have made good friends with my local Patek AD (how I got the buckle, strap, selvyt cloth, Patek magazines etc).
I think the quality is nice but keep in mind I have put a lot of money into it and without it being solid gold, it is not heavy like a genuine. So I would never take it off, of course.
That is about all I feel comfortable saying because I am about to be forced to sell it and I do not want to seem as a cheerleader trying to sell my watch.