I have one of these from Westendorf Mfg. Its called the brushcrusher. I purchased it to use with the John Deere connect system. It has it's purpose. But that is limited.
The "closing power" is from the dump direction of the FEL. On the JD with the pins on the bottom, all of that force is pushing in the opposite direction for what that area is designed for. If you aren't careful, you will bend the pins or even the loader pads. So no, its not the same as a grapple, I use it well, picking up piles of brush etc.. in my opinion it shouldn't be used to pick up piles of logs where it is uneven grabbing. It puts a lot of force on those pins and that area of the JD.
NOW.... Im not sure about the skid steer QA system, that system looks far more robust than the JD proprietary pins. So mileage may vary with the SSQA.
Quite a few YT videos out there on the mechanical grapple. Mine was the Westendorf 4200 Brush Crusher.
I got it because on the 2004 JD I was looking at $1500 for the 3rd function plus grapple. I think I paid around $1300 for the crusher a number of years ago.