Nobody likes a flat butt. Convex all the way.99% of thinning for me is thinning the tip 1/3 of the knife to restore geometry after sharpening out chips or fixing the tip.
I like thin tips and I'm hard on them so I end up thinning a little bit every time I sharpen.
I couldn't care less if the heel of a knife is an absolute axe. Fat bottomed girls rule the world.