The We-Vibe 2 definitely slipped like crazy but in my personal experience, the We-Vibe 4 stayed in place much better, including staying still and clamped (In a non painful way, may I add) directly over my clitoris. It was just a little too long for me as you can see, the clitoral arm on the 4, curves ever so slightly like a banana and what happened to me was that my clitoris sat inside that curve and most of the sensations were focused at the very tip of the clitoral arm, where it curved back into the body, for me, that was too high up my vulva and my clit is barely getting touched as it sits inside the curved bit that curves away from my body. I believe this is TOTALLY size dependant. Women with longer vulvas, or larger clitoris will probably actually find that the We-Vibe 4 hits the spot better than I did..me and my stupid small clitoris! grrrrr! When I pulled my pubic mound back and elongated my vulva and clit, it did become more effective for me, but still not ideal as the vibrations were at the top of my clitoral shaft. (I prfer stimulation almost direct at my clitoris)
Kasumi: The Doxy is the most powerful, and deepest vibrator I own. The vibrations are even deeper than the Lovehoney Deluxe wand, to the point where, on higher speeds, it is almost thumpy and can be a little too much (Even for this power queen)
If you go to my video reviews, and look for my "Doxy vs Lovehoney Deluxe comparison video, I explain a lot of the pros and cons of each, as well as turn them on so you can hear them etc. But to sum up....yes it is extremely deep, but sometimes I almost felt like it had crossed the line from gloriously deep, to painful thrumming. The lower settings were so nice. I personally cannot use the higher settings though. Not without padding between my body and the Doxy.