"Best" Apple ID style BEFORE I start iCloud?

As a long time Mac user, I have the old style "firstmiddlelast" name style Apple ID, with no email address. That is the Apple ID all of my iTunes Store purchases have been made under. It is what displays on the Account Page for the store.

I ALSO have a Mobile Me account which I still use to sync my devices with "firstmiddlelast@me.com" ID. This was a .mac email address before the MobileMe roll-out. The formats and spelling for the two IDs are identical except for whether they are appended with "@me.com".

I have seen quite a few posts about problems with conflicting Apple ID styles, including this issue with old style short Apple IDs. Currently, everything is working for me, purchasing with the "name only" ID and email + sync with the name@me.com ID.

I BELIEVE (but am NOT certain) that I need to set up iCloud with my name@me.com address to keep all my currently synced data working and transferred to the new iCloud system. And it seems like all my iCloud services should be under 1 ID, not 2 versions.

Should I go in and change my Apple Store ID from "name" to "name@me.com" to make everything work under iCloud? Will that cause any problems with my many, many iTunes Store purchases?

I would like to try and transition to iCloud this weekend, but want to set things up for success. Hate to lose the old shorter ID, but will do if it will avoid problems.