Currently the printer over cures the first two millimeters of a print. This is usually in the support base so isn’t usually noticed. However if you print with no supports it is noticeable. The result is a slightly thicker and less detailed base to your print, which abruptly ends as the over cure ends resulting in a noticeable line exactly 2mm up the print (assuming the z-offset is set correctly). If the over curing amount dropped off slightly each layer this line and ledge could be eliminated.
Also I have noticed in my prints that immediately following the over cure area I get more print flaws. I assume this is due to the sudden change in material properties.
It would also be mice for those who have the Z-Offset set correctly to be able to specify the thickness of the over cured area. Once the over cure is sufficient to adhere to the bed it is no longer needed so if my Z-Offset is right on and bed alignment gives me a difference of 0.1mm in height across my object being printed then an over cure thickness slightly more than 0.2mm or 0.3mm is probably all that would be needed.