Opinions differ but as far as I am concerned, 20mm vs 16mm - not much difference. The extra battery capacity and most importantly the extra weight at the bottom part would more than compensate for the additional 4mm.

The main reason I ended up parting with my TOHKBD2 was that the overall assembly was poorly balanced. Way too top heavy, with a very light and thin keyboard and a heavy main body with the screen above it. You are heading in exactly the same direction.