Don't shoot the messenger. Just repeating what I've heard.
I've never used one, but have read reports of ghosting problems and directions not registering. Also, the Retroblast review wasn't very favorable.
It has been debated in many threads, but the fact I was bringing up is that some have had these issues. The Ipac, which is also console compatable using adapters, is a solid encoder without the issues of the X-arcade.