Got my set of 58mm filter holder and lens adapters from Xume last week and I've been using them (so far with just the lens caps but I did attach one to each of my 58mm ND filters also).
I really like the design, and so far I only have one complaint/caveat. The original (pinch) lens cap will no longer fit once you attach a lens adapter so you literally *have* to buy a filter adapter for each of your lens caps as well as for your filters. That also means you just end up attaching your pinch lens cap into a filter holder which is then magnetically attached - so the pinch cap can still get knocked loose inadvertently and it can be somewhat awkward trying to lever the magnetic ring off without accidentally bumping the pinch mechanism.
What I'd like to see is either a design that lets the original pinch cap fit in place without an adapter and/or Xume selling their own reasonably priced (i.e. $5-10) lens caps for each filter size that have the magnetic ring built in. That way you could have a solid cap that fits with the magnet system, which I like very much, and you don't still have to worry about the pinch cap falling off.
All that said, so far no problems and I already plan on getting another set in 77mm for my other filters, and maybe one for my RX1's 49mm filter thread also. I really like being able to pop the cap or filter on and off the lens with a simple magnet, this is going to be SO much easier to work with filters from now on!
