my suggestions...

Either way, you’d better to be a MCP; to do that, do your homework at MS website so that you know your path.

As an application developer, you do need to know sql server database included best practices; as a database developer, armed with .net framework knowledge will help you to advance your skills.

Keep this in mind, with solid experiences in development will certainly help you get into the data management field in your near future (i.e. in 3-8 years), since you may be required to have both SDLC and ALM background.