At high amounts, the blur effect from zoom blur gets cut off (specifically with text, whether the text is rasterized or not. I haven't tested other shapes). It's related to the "add x amount of space around objects" setting (though no number actually fixes it. It is easy to see when you compare the effect in Illustrator to the effect in Photoshop.

You guys really need to work on Illustrator's effect system. It's the one thing no other vector app has, but some things don't work or aren't effective because we have less control than we do in Photoshop.

P.S. I also can't change the color of the Neon Glow effect in Effect Gallery.