Ajax,
During Axiom's in-house, blind testing of 'broken' in speakers vs. a pair right off the line, they could not discern between the two. Very few (if any) others have done similar tests with the vast majority of reports on break-in coming only from a consumer standpoint, one that is easily explained by our neural behaviour.
For obvious reasons, testing this this would harder to do at home, unless you have the cash to order a brand new speaker pair just for fun as well as the time to properly setup and conduct an honest blind test. I think companies post more about breaking in components as a marketing tool since it is a highly accepted concept. It is blasphemy if you say otherwise as the owner of Mcintosh Labs once found out.

Alan can tell you more about this although he has already posted such thoughts in the past. If i have time to find the link i will post it again.

"Those who preach the myths of audio are ignorant of truth."