I spent a good bit of time with that one last year. It's a great concept and very cool when it works right. Unfortunately for it, there is enough delay and errors that any type of keyboard broadcasting solution will be *much* better.

For example, when boosting my priest behind my hunter, I would have a command "shield self", which mostly worked well. The problem is that in the time you've spent saying that and whatever delay your machine takes to process that, you could whacked an unbound key on yourmaster to call that macro on the slave and likely be able to follow it with a fade, renew, whatever.