I did see the video of the JB grab working on the E10 some time ago, for me i just think a thumb would suit better.
The thumb is stored on the machine, so its always to hand, ive not got to find storage space in garage or shed as i would with the grab.
I've got a concrete drive to take up maybe next year, & i think pulling large chunks of concrete up with the bucket teeth & picking up with the thumb & bucket would suit better than trying to pull the concrete up with a grab, the JB grab doesn't look as tough as the bucket thumb combo, i think the grab would take a bit of a beating where chunks of concrete is involved.
I've got 2 old sheds to demolish, so I recon the thumb bucket combo would work better there, mind you i could prob kick them down with my big boots on

The manual thumb is about a third of the price of the JB grab, yes i know i wanted a hydraulic thumb, but the chances of me getting a off the shelf one for the E10 over here are slim at best.