mnblade,
Well it's really simple: when I hold my large Spydercos in my fist (like the Rescue) the "v" of my thumb and index finger fall right over the lock release. And if I'm pressing down on the back of the handle I can rock my thumb slightly backwards, without loosening my grip, and release the lock.
In fact, that is how I close my Spydies, releasing the lock and letting the blade fall with the unsharpened portion of the blade hitting my index finger.
Now, when I'm holding my Buck 110 my hand barely even touches the lock because it's at the end of the handle and out of my grip.
I'm not saying the Buck lock-back is stronger, only that I like the release at the end of the handle.
I hope that clears up my statement for you.
Cheers,
Allen.