Good Question. I wrestled with this for a while before buying my 150/150. I wanted to obtain the GW increase paperwork for this reason. HOWEVER, I don't think this is necessary. First, my disclaimer: I do not condone flying over gross, it is to be done at your own risk, it depends on the capabilities of your specific airplane, I am not responsible, use common sense. OK, that said, I spoke with an insurance agent before my purchase who told me he had "never heard of a claim being denied due to the airplane being over gross" during the incident/accident. So, I bought the plane. When I got my insurance paperwork (from Cananwill and the AOPA-GREAT deal, by the way-700 a year for a low time pilot), I read it fairly carefully and it didn't mention anything regarding Gross Weight, which suprised me. It listed a whole host of other things you can't do, but not that.
Now it's always possible I missed something, but that's the assumption I'm operating under. I'm sure there are some who will disagree. I don't think I'd ever fly it over 1760.