Functions fairly well. I don't recommend using too many at once, however, since the way this is coded relies on SMW's extremely slow VRAM update handler. If too many blocks are updated at once via that, you can get NMI issues like this. A solution for future versions would be to try and distribute block updates across multiple frames. Other than that, though, it works fine.
Whoa finally blocks are getting some love again, I never understood the whole use what we got or make your own in block tool mentality, basically rendering the block section to be as exciting as fine print on toilet paper packages. Which actually is incredibly useful if you have nothing else to read while your in there.