If you find yourself doing more reading than watching the actual anime during a sub, then you should probably improve your reading speed. It takes me less than a second to read a line of text and I do it while still watching the events on the screen. Unless you are watching on some huge 32 inch beastmobile of a screen, it isn't difficult to see the what is going on-screen.
It's not like in the current era of anime, that the characters move or do anything important while they are talking, anyways. Animation studios, generally, are too lazy to have characters do anything dynamic while having a conversation. Any dialogue during action or tense scenes is also pretty limited.
This is probably the poorest reason to watch a dub. Honestly, how would you go about watchinig a foreign film without subtitles (ex. Pan's Labyrinth)?
I know, I'm going to wait until this is poorly dubbed, the dialogue is butchered because I can't fit everything in, and it probably gets censored and edited, then enjoy it.
Great fucking plan, dubbies.
There seriously is no valid reason to watch dubs other than if you are already under the watch of the law for piracy.