There's not really any issues regarding alpha, I figured out that additive was what the explosions needed after playing around with the SpriteBatch modes. I have to add something in the object stuff to tell the engine if it's rendered additive or not, but you are correct.
The problem with using Photoshop is that I'm not really sure how legal it is to make the engine and provide the sprites on top of that to play with it, the best I could do was allow you to do that, but for most people it might be that they just want to copy the Decoder's output straight into it.
