I haven't, but I do trim a lot of hedges and can express a preference for the sort of step ladder that has rungs up both sides so it can be unfolded into a standard ladder ladder. I can straddle the top with a foot on either side which gives a nice stable posture for hedge trimming.
If you're doing something as high up as in that photo, like taking the tops out of leylandii, I'd suggest thinking about getting someone in while you sip on a G&T. It's the only way.