A buddy of mine has one and I've messed around with it. Awesome unit. We're both optic junkies and it's a unique piece for sure. He got it several years thru a trade I believe. The only other 1 I've seen was in a movie. If you have a chance to snag one I'd grab it. Best of luck
A friend had a pair years ago. Worked well and hand holdable but heavy ish as I recall. For tripod use he rigged a block of plastic or wood and a velcro strap to depress the stabilizer button for hands free stabilization. I was envious and stuck with my 15x. In big country he had an edge for sure. Haven't seen a pair since.
I've tried Randy Ulmers....the only guy I know that has them. He is a friend of friends and he said he used to carry his everywhere...even 3 D tourneys.
They are truly impressive....but huge. Its a mechanical stabilization process and I would be worried that the mechanism will wear out or need service over time.
I would call Zeiss and ask them about the 20x before purchasing.