The main point to me is requirements' modifications occuring during alfa and beta testing. Usually, at this point the scope of reqs should have a rather crisp form. If a customer feedback is to have an influence to the reqs it should be treated as a change request (CR) with a clear assessment wrt risk/benefit. The modified req entry should contain a reference to the respective user feedback. I'd rather have alfa and beta feedback reports as a standalone document as it is a product evaluation rather than a definition.