Isn't it between 12 and 14Bps, I think that the X-Board doesn't speed up the Bps but improves the Motor response time and I think it's a wee bit more efficient on the batteries too.
They advertise 14 bps, but I think it's more like 12. You can only get a reliable feed of about 10-11, although there can be spurts as high as 14 I suppose.