To sleep high or low?

At the moment my son (4) has boring Ikea furniture in his room and I want to replace all of that with something fun but practical. We thought he might become more enthusiastic about going to bed if it's somewhere high. And theoretically there would be more space in his room, though this is not such an issue.

I've found some cute arrangements that I really like (more images here).

I'm just not totally convinced yet. Some questions nagging me are: how dangerous is it for sleepy children to walk down those steps at night (to go to the toilet)? And the practicality of changing bedlinen? And don't they ever fall out?!

So what do you say: normal bed or one of these? Did you have something similar as a child? Or if you have children, what's your experience?

What do you think would fit best under the bed space: a desk, a reading area with a sofa (but don't kids read on their beds?) or a wardrobe?