My drawing pad has the 6x4 active area. The total pad size is 11x7. But to drive home the point that she 6x4 is fine, my pad's surface is visibly worn where I do the most work - an oval about 3x2 in the center.
By "visibly worn" I mean that the surface is slightly discolored and much smoother than the rest of the surface. It's essentially polished.
Yes, the pressure sensing ability is great, but I still like to lower opacity levels of whatever tool I'm using to ensure I can build up color.
For example, for German camouflage mottles I usually use the 9 or 11 pixel fuzzy airbrush tool set to 30-40% opacity.