GX Remorse,
I'm sorry to here you have had problems with your GX. My wife and I agree that this is the best car we have owned EVER and that this is the first of hopefully a long relationship with Lexus (she wants a SC! :) )
I feel your pain though when it comes to problems with a manufacturer and then going thru "arbitration". Fifteen years ago, my wife and I experienced the same senario with the one who makes "Ram Tough" vehicles. We went through a long three year legal battle which by the end of we discovered that our lawyer was on the manufacturer's payroll and the judge (who was elected) had her campaign financed by one of the local "Ram Tough" delereships. The judge declared the case a "draw" and we ended-up with the manufacturer reimbursing our legal fees (about $1400) and we kept the piece of "Ram Tough" junk! Oh... we also had to sign a statement that IF we EVER bought another vehicle from this manufacturer (no matter what the brand), we could NOT file a lemon law claim against them. Needless to say, we have never even considered owning a "Ram Tough" vehicle since. In the words of "our" lawyer, "well, there are millions of other suckers out there who will buy them." :o
But back to our GX...
Actually, the clunk in our GX is not that bad, it only happens about one in every 20-25 brake/accelerate cycles. But, when it happens with Mom in the car, that's completly unaceptable!! ;)