I had the occasion to drive on sand on the ocean beach the other day with my 4wd HiHy. I expected some issues especially where the sand was the driest and heavily rutted from the other vehicles, but I did not detect any wheel slippage or loss of traction at all.

While I was there an older 4wd Tacoma with wide mudder style tires had problems while in 2wd mode. He basically got stuck and had to shift into 4wd to get himself unstuck. I motored through the same area at about 2 mph and had no problems at all.