I regularly "beach" my H260, but I do it VERY carefully. I nudge the boat up to the sand until it stops. The retracted centerboard protectes the hull from damage. I've seen pictures of Hunter water ballast boats settled on mud in tidal areas and apparently there has been no problem because the weight of the boat is distributed along the hull; however, I would be reluctant to rest the weight of the whole boat just on a retracted centerboard. My thought is that you don't want to do any flexing of the hull that would compromise the seal of the ballast tank.
That said, it appears that over time the dings and scratches of the centerboard could allow water to compromise the board and require its replacement. IdaSailor makes a composite centerboard that is not subject to damage. Ideally, both the centerboard and rudder should be replaced with the IdaSailor product.
Problems with the centerboard and rudder are easily fixed, it just requires investment in a long term solution such as the IdaSailor product. I'm trying to delay that day as long as possible.
Just thinking about modifying a Hunter water ballast boat with a vertical retracting centerboard make my head hurt...