I suspect you will get more 2D processing speed in Blitz2D than BlitzMax. Why? Because BlitzMax relies on 3d acceleration (GL and eventually DX) to do its 2D stuff, which generally isn't faster and is certainly less compatible.
Advantages to using BMax would be scaling/transparency etc, but also cross platform compatibility.
Advantages to using BMax would be scaling/transparency etc, but also cross platform compatibility.