Till recently when Google Apps Premier email had a maximum storage limit of 25 GB, my email email@example.com got full, and I was forced to purchase and make another username for myself firstname.lastname@example.org. Very recently Google has removed that restriction and now any amount of storage (upto 16 TB) purchased, will be shared across Google Drive, Google+ Photos, and now Gmail.
Therefore, due to inconvenience and expense occurring in maintaining two user accounts for a single person, I have decided to dump my second email and transfer all the emails (in Inbox, Archived, and in other labels) to be copied or moved to my first email, with label structure intact.
Drive is not an issue since the ownership of entire Drive content could easily be transferred through a very easy way available in Google Admin Consol. It is the email which is a real pain and about which Google seems to have not done or said something about.