I notice the table alpinerabbit posted only discusses stresses on the down tube and rear triangle, so I'm assuming they didn't test any of the trainers that clamp the forks. Those are the ones I'd worry most about.
Can you even buy those anymore? I don't think I've seen one in years..... And yes, the idea of clamping both fork and rear triangle makes me nervous too.
I don't worry too much about putting my bike in the trainer.