Value of Iniative. Is it worth going first?

[Pickford]

For what that's worth, at least; it was certainly intended to override all other sources, and the only reason to suppose it wouldn't is if you favor a particularly nitpicky reading of certain rules, and completely ignore all manner of common sense. In practice, that's a bad idea, so RC should be considered a primary source for any actual game.

Actually I found it curious for another reason, but was clarified by a google search (found on minmax board):

Originally Posted by Chris Perkins, speaking on behalf of WotC
When we release errata, it will always be free.
It logically follows that if the change is rules is not free, it is not errata. The changed text in the Rules Compendium is not free, therefore it is not official errata.