*tongue in cheek*
Mary, I'm surprised at you. Warning someone against getting an Ensign because you heard about some of them having trouble in a blow. Why, I saw a catamaran capsized the other day, don't buy a cat!!
*tongue removed from cheek*

Here's the likely reason those Ensigns had trouble.
Ensigns were designed to be sailed on salt water. The flotation was added to be sure they would float also on fresh water, which is less buoyant. But, any serious racer of Ensigns (not me), and any Ensign that has had any amount of work (also not mine - yet), has had the old 1965-era open cell flotation removed, and replaced with equivalent buoyancy closed cell flotation material. Sometimes, in the pursuit of that extra nano-knot of speed necessary on this kind of monoslug, the owners "forget" to put in enough flotation, taking the chance they will never need it. Along comes a big gust, leeward rail goes under, and presto - you're sinking.

The equivalent activity on a NACRA would be to remove the bulkheads inside the hulls and leave the portholes off -- "to reduce weight", go sailing in a heavy air, and then act surprised when you capsized and had trouble righting it.