Here's what Klippel (the guys that make the test sytems mfrs & engineers use...) has to say;

http://www.klippel.de/download/bin%5...easurement.pdf

The meat is in the last 2-3 pages (complete w/graphs & charts). Note the reference to non-linearities due to compliance changes... when "broken in", the suspension actually becomes stiffer at travel extremes, but more compliant at lower excursions.

But it's just a brief change... at times on the order of seconds. Therefore, it's not a permanent thing like we normally think of as "break-in". I like to think of it more as "warming up".

Added;
For those that never push their woofs anywhere near Xmax, it's a non-issue.