I have no problems with my cats sleeping in my bed.
Yes, they do leave behind quite a bit of fur but I am not allergic to fur. As for the question of whether I would crush my cats when I turn over in my sleep, it's not an issue with me. For a start, my cats don't just sleep in my bed. They actually sleep on me. I usually sleep on my side and my cats would sleep on the side of my torso. Their favorite place is the part between my shoulder and my neck. This part has become kind of like a position of privilege.
However I noticed that as my cats grew older, they are sleeping less in my bed. Maybe they are making way for the kittens or maybe they are spending the nights hunting mice.