I have attached a simple map used to explain differences and consequences of using components on various stages of evolution.
It caused nervous giggling, looks and embarrassment:
You cannot tell that implementing an inhouse CRM you are competing with Salesforce but you will not get even close to their efficiency., but you will have to solve all the issues they have alread solved.
There is no reason to be embarrassed.
... if you know maps, if you know the evolution, but you still want your own CRM - shame on you!