Hi Jerry, just my thoughts, after having sailed both types, ie light & heavy cats :
Lighter is safer, with more stability. I`ll justify this as follows :

Most designers want a certain level of performance when designing a beach-cat. Relative performance is one of those things, ie Prindle would never have sold a single P16 if it`s performance was nowhere near that of the H16, it`s main rival at the time. So heavy boats are generally designed with more sail area than lighter boats. They have the same Power-to-weight ratio as lighter boats, but tend to become overpowered in heavy breeze.
If you were comparing two boats 16ft long, identical hull shape etc, one weighed 100kg with 16sqm sail area, the other weighed 150kg with 24sqm sail area. Assuming identical crew weights, you`d find the following :
- Boat 1 (light) would handle stronger winds than boat 2 (less sail area : crew weight ratio).
- Boat 1 would accelerate quickly in gusts (lower inertia), meaning that less of the force of the gust would be prone to capsizing the boat. Boat 2 (heavy) would resist acceleration, and the initial force of the gust would want to push the boat over before pushing it forward.
- Boat 1 would sit higher in the water, since 1kg of boat will displace 1liter of water, so boat 2 will have to displace 50liters of water more than boat 1 before reaching it`s displacement. This allows boat 1 to appear to have more bouyancy, in fact they have the same bouyancy, but boat 1 has a lower dispacement, meaning it will ride higher over chop & slam the beams less often.
- Boat 1 will be easier to right, less sail area = lighter mast needed to support it. To me, this is the most important factor. If I can`t right a boat, I won`t take it sailing. Ever. (Here I must disagree strongly with Mary - if you can`t right the boat by yourself when sailing with young children, I`d insist you stay ashore. Choose a boat you CAN self-right. If it`s a laser, then rather sail that than a Hobie 18. You WILL capsize one day or another.)

Yes, a lighter boat will be more responsive than a heavy one, but this makes it no less safe for beginners. just start off in lighter winds and build up gradually as your confidence improves.

And remember, this is only my OPINION.

Cheers
Steve