Never been in anything really bad but one man's bad is another man's OK in my experience. I've flown with other pilots who have commented how rough it is and I have barely noticed. Tight straps, that's the answer.
I did run out of control authority landing a glider once. I was caught out by a line squall and bunged on another 20 knots to my approach speed to make sure I still had control. I didn't, the last 100 feet or so were with full left stick and rudder just to keep straight while the hail was tring to make a good job of turning the canopy opaque. I remember being about 30 ft off the deck with about 70 knots on the clock and in the last ten feet the speed just dropped in half a second or so to about 35. Just lucky I landed OK albeit a little sideways. Although no luck involved in making the decision to come in very fast which is what saved my bacon.