Upload & Sell: Off
I wouldn't trust my 3 by 4 softbox on it
FWIW, I've had no problems w/ the PCB foldable one or a Plume/Quickring combo in that exact size, except when yanking off a grid one-handed while it was on a stand (stupid thing to do).
Put the fingers in the speedring...spin it around to make sure you didn't miss one.
And yes, I hate the Balcar mount too. I like the Speedotron one a lot better, though some people have said it'll pop off if you spin the modifier the wrong way, so there seem to be haters for each mount A few Elinchrom friends have thought it their mount was fiddly too (though no complaints about secureness).
The industry really should have gotten together to come up w/ a standard robust mount, but then they wouldn't be able to lock you into a system...
And the Balcar mount is ancient...they're a 1956 company...