Using palm tools while holding the work in the other hand is very much my preferred working method. However after starting a few carving projects that seemed to call for heavier cutting and also re-discovering some larger carving tools I had acquired earlier I constructed some work holding aids that would help with that work.
I have also experimented with using a lighter weight board version, without the bench hook cleats and using it in the hand with palm tools in the usual way or clamped to a small table for very light mallet work A common and useful method for holding small pieces of relief carving is gluing them to a flat board with a paper joint. However I wanted something that would enable frequent quick release and re-attachment.
The board has a grid of evenly spaced holes that accept screws to position cams that hold the work in place. These cams hold firmly and safely and palm tools can be used while holding the board in the other hand. However unless you do intend to clamp the board down to a rigid bench, and use a mallet or conventional carving tools using both hands, then I can't see much advantage over totally hand-held.