Unfortunately, there is no simple answer to this question. The real question you need to ask is does it benefit the business to upgrade? How will it improve the business? If there is no business related reason to upgrade the framework then you shouldn't. In the future at some point it might be cost effective or beneficial to move to a newer version of a framework. Software is simply a tool to get business done. This is a fact we as developers often overlook. :-) Good luck!