My Opinion is you must Read This Article then you can at least ready for the change.
Preparing for Microsoft Dynamics CRM 2013
One another thing - myself and my team (Dilan , Madushanka, Anusha, RUWANI , Madusha , Tharinda , Randika , Eranda , etc . ) started developing custom CRM system from the scratch 2 year back and we named it as "Orion" and we did the great job . http://crm.bpoconnect.com/