I Would just like to add my voice to the many iTunes Match users impacted by this stupid 90-day rule. You do not even get a warning from Apple to say that switching your account will subject you to this stupid rule. Not sure why 90-days was selected instead of something more reasonable like 10 or 30-days. I guess I will not be making anymore purchases using my UK account while on business. Lessens the value of Match to me.
The people responding in this forum are just other Apple product users like you, not Apple itself. Apple Support Communities is primarily an end-user to end-user (i.e., users like you helping other users) technical issue support feature. Feedback will likely get more attention if you send it using:
http://www.apple.com/feedback/ - Apple products feedback links
It is there in the documentation which nobody ever reads for anything
iTunes Store: Associating a device or computer to your Apple ID - http://support.apple.com/kb/HT4627
There's no official statement I know of about the wait period but you can conjecture the effect it might have on deterring illegal music sharing.
90-Days and counting...
