I have used both the wedge and the wing. They are both great, but the wing is by far my favorite. The wing sits a little higher, and is rounded at the edges, so you can easily put the wing under your lower abdomen for support, and the rounded edges allow you to sort of rock back and forth... I guess movement is easier than the flat base of the wedge. Also, the shorter hight of the wedge is not as comfortable, for me anyways.
You can also use the wing under your backside, the same way you do the wedge, but it,s going to lift a little higher, and it's not as gradual. I have on occasion added a regular pillow under my back for extra support when using the wing this way. But to me, the wing offers so many more options, like hands free play that it's no big deal to grab an extra pillow for under my back... There is never a risk of getting the regular pillow dirty, so it doesn't bother me.
Another thing, smooth in texture toys made out of, say silicone can be used, but materials like hard plastic that are slippery slide around too much. I have found very few toys that I cannot use with my wing.
The cover on the wing will most likely have to be changed more often than with the wedge, if you are riding it. I wash after every use. However, I read about some covers that you can buy from sport sheets that just cover an area around the toy insertion point, that's way the mess gets on the small cover, not the whole wing cover.... Sounds soo convenient, I think I am going to try to find some.
I also want to mention that the wingnand wedge are both very firm foam, they hold their shape very nicely and the covers hold up very well. My wing gets washed at least once a week and I have had it for several months and it still looks great.
To me, the wedge is kind of a ine trick pony. You guys mentions double penetration... I have not tried it that way, but the toy insertion point is on one egde of the shape, so your back side is easily accessable while riding. If you are thinking of riding with your bum, you will just have to scoot forward a but, easy as pie.
I really love my wing... If you can't tell. Haha