There are two critical questions to evaluate.
I cannot say that there is any significant risk to continuing to use your custom implementation, other than the risk of your time and ability to support the application. We have worked with many organizations that have developed their own CRM solutions and are happy with them. The challenge comes when the lead (and sometimes sole) developer gets too busy or leaves the organization, or when the number of users exceeds the performance capacity of the solution. And there is always the issue of keeping up with the feature requests from the users.
Dynamics CRM provides a great balance of simplicity and ease of use with some fairly powerful tools for customizing the user interface; creating completely new tabs, screens, objects, and reports; and workflow for managing tasks and business processes. Plus, the Outlook user interface has a significant positive impact on user adoption. Depending on the growth and needs of your organization, you might want to evaluate Dynamics CRM. Microsoft provides a variety of options for evaluating the product; visit their page on evaluating Microsoft Dynamics.
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