"If you are not happy with your current attorneys performance, you're certainly free to file a complaint against him with the state."
While this is true, lots of clients are dissatisfied, but that doesn't mean the attorney has done anything wrong. I would absolutely encourage the poster NOT to do this until there is some reason to believe the attorney has done something wrong.
"You seem to be paying out a rather exorbitant amount of money and getting very little in return."
The case is not over, so we can't possibly know what outcome will be. In any case, $10000 is not at all "exorbitant" (i.e., "Exceeding all bounds, as of custom or fairness") for a full year's work (it's only 40 hours at $250 per hour, but since it appears there is at least a partial contingency agreement here, we can't really analyze these things too well).
"You should keep a copy of your request, and send it to him by registered mail with delivery confirmation service."
On the other hand, a person can decline to accept certified mail, in which case the lawyer will never receive the request. Certified mail is pointless in a situation like this.
"I personally wouldn't pay him another dime if there hasn't been any significant movement on the case."
This is one of those situations in which a "what I would do" statement sounds a LOT like advice, and it may be very foolish advice based on the minimal information we have.