Even your venture cat should be able to recover from a turtle based on a couple of things:

a) your mast is sealed and does not leak. As long as the mast remains filled with air, it will want to float.
b) you place your weight properly to get the boat back up from turtle.

To right the boat from turtle, you need to get hold of your righting line (usually tied to the middle of the front beam or mast base) and sit on the corner of the boat that is farthest downwind. This might mean on one of the bows or one of the sterns. Using the righting line, lean your torso out as much as possible to try and sink that corner of the boat - and wait. It will take a minute or two, but the boat will slowly start to come up. Once it begins moving, it will move faster and faster and - stay on that corner as long as you can. Pretty soon the boat will but up and laying on it's side. There is a trick to getting it pointy end up from there too - let us know if you would like more info regarding that.

I sail a 20' Nacra6.0NA and have turtled a couple of times (I do not have any sort of a mast head float). It was no problem to get it upright again (probably about 3-4 minutes).