I think it could still be a potential 'toggaleable' option, but it would require a bit of work. Maybe we could put this on a 'once the main stuff is put in, then...' list?
I suppose it would be impossible to draw some tiles with different colors, since game is paletted, and only "lighting" level could be altered. But lighting is dynamic entity, so it would be kind of indestinctive from another, neighbor tiles with different lighting.In any case, I won't vote for doubleclick walk.
I tried this in UFO Extender, and I can say I found doubleclick very comfortable