Even if you're five-boxing, if you go into a BG or any other raid you won't always have leader to pass around. No matter how big your box is a virtual party would fix this I assume. As is you would always have to have the party leader to use this addon, which is a deterrent for me as even though I will almost always have leader, I don't want to get used to it for those times when I don't have it.

Keep at it, it looks like this is going to become a great addon for almost everyone who boxes wow in the future.