It is fine to leave your repos enabled for day to day use except for the extra-devel one.
This one should be enabled only, and i mean ONLY if you want to install a software which is not available in other repo.
Software here are often buggy and can cause unstabilities to your phone.

The only place where you will see difference will be when your app manager/faster app manager update his application list. The more repos are enabled, the more time it will take to update.