whether the secondary grind is hollow or flat shouldn't have much effect on the sharpening.
the edges are actually slightly convexed, typically ground to about 30 degrees inclusive.
crk recommends the stones set at 40 degrees so they hit the actual edge rather than the convex bevel.
ive always had issues with convex edges, so i normally flatten mine on an edge pro, then use the ultra fine rods to touch up.
stropping should do the job well enough, though.