Apple ID @mac.com on iPhone, @me.com on Mac: does it matter?

Somehow in setting up all my devices for iCloud I managed to have my Apple ID as @mac.com on my iPhone and iPad, and @me.com on my iMac. I never, ever use the @me.com version of my address, so I'd really prefer to change my iMac to @mac.com, but if I go into iCloud prefs there is no way to change the Apple ID.

My question is, assuming there is no way to change the Apple ID (which is really not very cool), does it matter that the accounts have different names even though they are the same account?