RE: cut on contact broadheads
Just a possibility that your bow wasn't/isn't tuned as well as you were thinking. Maybe it is the broadhead (though I've never heard bad reports on the Montecs), but could just as easily be the fact that (and I'm taking a guess here) that you've been shooting with field points most of the summer, and that a very slight trouble spot has been allowed to surface now that you've switched to fixed blades. Remember, any fixed-blade broadhead is going to magnify any tuning inconsistencies "covered up" by shooting field points, IMO.
You can try to bring your field points and your broadheads' POI (point of impact) together by moving your rest in toward your bow very slightly (I'm talking 1/32"or so to start with). Re-shoot both your broadheads and your field points. Eventually, you should be able to hit them pretty much spot-on.