Yes, its correct, you can get higher speeds than theoretical hull speed, (which is a calculation based on hull lenght at water line, based on bow wave height and separation between the bow and aft waves), if your hull starts planing, meaning it rode the wave and is now "surfing" on it, so the wave is no longer an obstacle, or if as you well said, when healing, the water line increases due to the overhangs, but so does drag and other limitations.
Please check these threads bellow
and this site. In this site if you place the cursor over the rectangles, it explains what is what.
Hope it helps