Your own CRM

I wanted to get some feedback from the group on maintaining a second CRM with "your" contacts and leads. Basically a formalized version of the spreadsheets most of us keep anyway.

The big advantage I see is you'll have something you can take with you to any future role and not have to start from scratch. Disadvantage, you would need to log at least the major events twice in both or at least data dump periodically.

Good idea, bad idea?