Same for me, the ability to offload the most frequently used keys (space, return, backspace, shift, ctrl/meta/super) from the pinkies to the thumbs is probably

Same for me, the ability to offload the most frequently used keys (space, return, backspace, shift, ctrl/meta/super) from the pinkies to the thumbs is probably the greatest benefit of a good split design (Datahand in my case)