I actually am described very well as a 7w8 sx/so.
Especially if you look at the descriptions of a (I hate this word but I have to use it) "healthy" 7.
I am not at all accurately described by the 7w6 description, and not nearly as well by the 8w7 as by the 7w8.
So for me, it works just fine.
For others it might suck ass.
No system will ever describe everyone accurately, or even to everyone's personal satisfaction.
I'm not hatin' on highlander's OP, BTW, I'm just contributing my personal experience on this topic as I did alot of reading between the "wings" 6,7,and 8 and how they do/do not relate to me.