As I understand it, Laidback extended stern and bow. The stern previously ended below the surface, which will create serious drag, especially at relatively low speeds. (At high speed, the flow will release and drag drops a lot.) Even if he had not increased the rig power and moved the rudder
aft, there cannot be any doubt that the boat would be notably faster, and behave better in most situations. The increased wetted area is insignificant compared to the removed stern drag, the increased lenght to width ratio and the resulting improved wave pattern. It's possible to get really nerdy on this, but I'll stay on the main points for now.
The added stern lenght may have affected steering
a bit, but as most such sterns are rather shallow and have a round profile, I'd guess the effect would be close to nothing. Moving the rudder aft, the steering would be better than before. The bow extention will normally be sharper and have a better "grip". Thus this extention will cancel out the steering advantage mentioned, and the boat will probably be very similar to what it was before, but faster and generally better. It was overloaded, but now will have extra load capacity. It's a bigger boat with less resistance and more power. It will be a rather much faster boat. Such changes are much more work than they seem, but may be worth it, and may also not be. Depends upon the boat and the needs.