They used to sell this a while ago but pulled it from their store for some reason. They wisely have chosen to reintroduce it. My opinion is that is offers another alternative that, while definately not for everyone, will satisfy some people's requirements. I get questions sent to me on a somewhat frequent basis about person's wanting to build controllers that hooked to the PC and could be, easily, used with a DC, PS2, or Xbox. Those persons would be the market.
As far as the X-arcade's encoder being buggy, I never once had a problem in the six months I used mine, and it saw a ton of gameplay. Once I built my custom CP and used Andy's product, I could tell there was a definate difference in response (the I-pac being superior, obviously), but I don't consider the X-arcade's encoder crap by any stretch.