Well, I may be somewhat qualified to speak about this, because I
have bought my wife a Sybian. I have a few things to say about it. (I didn't answer the poll since I'm not a lady).
First, those who say you can do the same job with a $10 vibrator don't know what they are talking about. Standard vibrator orgasms are quite nice (so I'm told). Sybian orgasms are profound, prolonged, earth-shattering...and just about any other superlative you could apply to them. Granted I am male and haven't experienced this myself, but I've observed it first hand and it's just unbelievable the reactions she has. It makes me wish I could be a woman for a few minutes so I could try it myself!
Second, we have used all the attachments at the highest setting without damaging her body in any way. I can understand being skittish about getting on one if you never have before - my wife surely was, but she got over that in a hurry. Also, she is a very value-conscious woman. When I surprised her with it I asked her to try it once - if she didn't like it or didn't think it was worth the money, we'd return it immediately (the Sybian folks do allow for this within a couple of months or so, if I remember right. You do have to pay a fee - about $90 last time I checked). She never said a word about returning it after she tried it the first time. One thing she mentioned was how relaxed she feels after a Sybian session. She compared it to the feeling she gets after having an hour-long professional massage.
We don't use it all the time - maybe once a month or so. Generally we only get it out when the kids are away at Grandma's or something - mostly due to the sound of the thing, as someone correctly compared to an airplane engine. Yes, it's very, very loud. Probably not appropriate for apartment dwellers.
Anyway, I'd be glad to answer any questions anyone has, and if you want the female perspective I might be able to get her to answer. For now I will just say: I have seen my wife have many orgasms in various ways, and in terms of sheer intensity, absolutely nothing compares to those she has on the Sybian. Am I threatened by this? Hell no! She still wants to have sex with me, and nothing turns me on like seeing her get off the way she does on our Sybian.
I will say that I have heard that some women try the thing and just don't like it, but that's to be expected with anything. I'd say if you've got the money and have tried and enjoy other sex toys, give it a shot. You might just be surprised.