I've used one since last summer, including a 6-week road trip in Australia. In general I'm very pleased with it, although I do see a potential risk of the props getting 'stressed'. You have to be careful when mounting the skeleton as the props tend to rotate slightly and they might get bent when you close the clip if you don't double-check - make sure they are nicely centered in the arms.
I found the best way is to hold the skeleton upside down in your hand or on a surface then lower the spark down into the skeleton, if you see what I mean. I also have to remember put on my gimble guard first.