I've been using Schoeps A20 and A20S mounts for well over 20 years now. Yes, they're expensive but for my money they're actually not bad value. Like most things Schoeps, the up front cost isn't cheap but unlike the vast majority of mic manufacturers the aftersales service is excellent and ongoing support is quick and very reasonably priced. The bits that wear out or break - the mic clip itself (especially if, like me you abuse them by fitting the larger diameter Neumann KM8x and KM100 mics in them) and the plastic bases which seem to crack after several years of quite heavy use (the current A20 mounts use metal bases so that won't happen any more) and the elastics which just wear out - are all available as spare parts and are cheap to replace, extending the life of the mount indefinitely. I keep packs of spare clips, bases and elastics in my mic mounts cases for any quick repairs when out and about. And of course, swapping an A20 to an A20S (or vice versa) is just a matter of spending a few pounds on a set of other elastics and five minutes to swap them over.
However, for all the reasons already mentioned, I'm now gradually changing over to the Rycote Invision series mounts. Some are a little less compact than the Schoeps mounts, which has raised comment a couple of times for in-picture work but they're extremely effective and so far seem to live up to their claim for being indestructible. I used to have over seventy A20/S mounts but I'm now down to around 30 and will gradually whittle it down to a handful or so. I still prefer the A20S for mounting the UMS stereo bar as none of my Rycotes seem to balance with that as well as an A20S and its double cable grip works better than the Rycote one when there are two cables going to the stereo bar.
Incidentally, I recently bought a Schoeps V4U and it came with a Schoeps branded Rycote USM shock mount so Schoeps seem to agree with the quality of the Rycote product.