Originally Posted by cfircav8r
Being under powered will not make a plane harder to control. Aircraft setup, design, launch technique, and control inputs are the reason for launch problems. Under powered planes just won't climb or hold altitude, but will still be fully controllable, although many people believe that if it won't climb vertically then its under powered. The best thing to do is to learn what forces are involved in the hand launch and the techniques and control inputs needed to control, and/or work with those forces.
That's 'sort of' true but flying a plane that has very marginal thrust is actually really hard because the plane is constantly flying on the edge of a stall, and even doing a gentle turn can cause it to fall out of the sky. Having a little thrust in reserve does make a plane much easier to fly.
Having good thrust also makes hand launching much easier because the plane gets up to flying speed quicker, even if the launch is poor. This is especially true for heavier faster flying models where it's hard to get the plane up to flying speed by throwing alone.
With my 3D models all I have to do is point the plane up, open the throttle, and let go... and away it goes straight up
Try doing that with a plane with marginal power.