I`ve used them many times because I have slight latex allergy. They are not fully inserted in that the outer rim remains entirely outside the vagina. I personally consider they give a sensation much closer to bareback, since the friction is all on the skin of the penis, rather than on a layer of surrounding latex, and they have the enormous advantage that once you`ve popped you don`t have to withdraw immediately (because it can`t slip off) but can take your time and let your penis subside and slip out on its own.
I have introduced several wg.s to them in the past, and most have been quite happy to use them.
However, they actually cost about £4 each (I always used to keep my own supply), so I wouldn`t pay an extra £40 for the privilege