I've dropped my Bent Graduate in the sink a few times, as well as a few inches onto the shower floor. It's still doing just fine - no cracks, scratches, or chips of any kind.
If you're like me and you sit or lay down in the tub during shower-play, I wouldn't worry much at all. If you're standing, it might be trickier, so perhaps try something with a good, easy-to-grip handle. But most glass toys are incredibly strong. Just keep up with regular checks for damage and you should be fine.