Vic
Urgh. Very disappointing quality there.
Even without the twist it doesn't fundamentally look as well made as one would expect for the money. Especially given the reputation from being the original.
Viewed from a DIY perspective I'd be drawing something rather more beefed up as the long arms make the device obviously vulnerable to twist if loading is unbalanced. One reason why I never got round to making some was that there looked to be various devils in the details between something that "sorta works OK I guess" and "works really well". My needs were never so great as to justify a development project. In my experience such efforts are always third time is the charm, fourth and more are just right.
As I recall it the one time I saw Crab Clamps they seemed overall more robust in concept and execution.
Clive