you have it reversed.
V bottoms will rock and are less stable.
Flat bottoms are more stable.
V bottoms cut thru rougher water better - good for larger bodies of water.
V bottoms also reduce the surface area in contact with the water as you get up on plane, and consequently get better fuel economy and higher speeds.
V bottoms also require deeper water.
Flat bottoms will run in shallower water.
Flat bottoms will ride rougher in rough water and will pound and slap the water.
Flat bottoms are better choices on smaller inland waterways.
As far as steering, they both handle about the same, whether you are using oars or a motor on the back.
Good luck.