I found the Sanrenmu 702 to have an annoying flaw. Oddly, it was clumsy to open with the thumb stud. That, combined with the thumb stud placement. I remedied the configuration by removing the thumb stud altogether, and using a Dremel cutting wheel to add some jimping on the back tang of the blade near the pivot end. This allows one hand opening using thumb pressure on the spine, sort of the way one might use a Bic lighter.
The 721 is another one hand opener Wharncliffe, with a thinner, skeletonized handle, a thumb hole rather than a stud, and a pointier, thinner tip. It also has a true straight cutting edge, like a Needs Work, and unlike a Leek and 702 which has a slight curve.