I've seen the brand new Tiger HUET trainer in operation in Darwin. The rig is a full tandem sized cockpit mockup, without instruments or actual seats, everything is stainless steel and she's suspended above a crystal clear chlorinated pool at a lovely temperature. The pilots get in, the rig is lowered at a nice slow pace into the pool and lazily flops over on it's side, the guys unstrap and swim out of the cockpits.
That's the preparation for a stack in the water with blades exploding everywhere and turbulence and falling off the side of a boat fifty feet into the sea upside down.
Then again, a more realistic HUET trainer would be a rather hard thing to build if it was to replicate a ditching with some realism.
I guess it's better than nothing.