Yeah, I do let my cat (who we call the very original "kitty") in my bed. She used to do it a lot-she would push the door open, mew once, and come in. I would respond by calling her name several times in succession ("kittykittykittykittykittykitty") while scratching. Then she would jump up, mew once more, and sit there. It was pretty funny, actually. She always lays JUST outside of comfortable reach. Lately, however, she's been VERY fond of sleeping on my sister. Not with. On. It becomes better when she kneads first.
to answer your question on crushing, I doubt the cat would be in much danger. Unless you're a very big person who rolls around a lot, the cat should be able to not only free themselves before they're pinned, but also let you know in a very painful "fun" way that you're "attacking" them.
