The problem with voice changers without options to tweak it is that it all depends on what your voice sounds like going in the voice changer. If you sound nothing like him, then you're probably not going to sound anything like him when it does it's magic.
That said, would like to hear what it sounds like and see whether it messes with amp feedback.
I will say after looking at the ebay link, that the speaker and mic are going to be absolutely terrible; they're worth pennies.