New tires question...

I switched from GatorSkins to Michelin Ironman tires (similar in profile to the Pro2's) a year or so ago.  Simply put, you're going from a treaded to a non-treaded tire.  I found that while the Michelins are faster in a straight line, they don't do as well on tight curves, especially in wet or damp conditions.  I scared myself a couple of times in fast turns in the wet until I got used to them.  I suggest you ride on the new tires to get a feel for their handling characteristics before racing on them, particularly if you're racing on a technical course.

Tires really don't need to be broken in per se, but it is wise to ride newly mounted tires and tubes to make sure there aren't any problems like pinch flats, etc.  Speaking from experience, changing tubes in a dark transition area while holding a flashlight in your teeth is not the best way to start a race day. 

Mark