When playing with this do take care to keep your fingers clear. I just smashed my fingernail pretty good playing with one of my 3-ton jack stands, 'cause I'm a clumsy idiot...fortunately I didn't really have any weight on it at the time.

Mine requires a fair bit of force to disengage under load but I suspect a sudden impact would do it. I consider this a design flaw -- by shaping the ratchet teeth differently they could have made dislodging it under load outright impossible.

A pin would be the ideal safety because it would also protect you in the event the ratchet pawl failed. I'm be tempted to drill mine for pins but I'm afraid of weakening them.