I attended one of Tony Marchaj's lectures that included a discussion on the crab claw
rig. In essense it produced a very large amount of drive for its drag and side force. It offered a lot of potential for small light weight, low stability craft. As I recall the short comings is that it did not point very well and so would not be well suited to a higher performance hull form. There are also issues that aspect proportions had to be within a fairly narrow range which made reefing for heavy air, or even dealing with a wide wind range, rather difficult if not inherently impossible.
Jeff