FAZ, I'll answer a question that you didn't ask and suggest that you consider the 17-55 f2.8 IS for the 7D2. This lens is very sharp, focuses quickly (great for court side volleyball), and includes IS. Plus, the prices are dropping.
The optics are 'L' quality, but the weather sealing and build isn't. Unless you are particularly harsh on your gear or shoot in the rain, I wouldn't worry about build quality differences.
I have no clue what you shoot or whether a FF body is in the near future. If you're looking for a good zoom for wide to moderate telephoto focal lengths on a crop body, the 17-55 is tough to beat. My interest is primarily kids sports, events, candids, and portraits. For these subjects, I much prefer the 70-200 f2.8L IS II. Now that I've upgraded to FF bodies, this lens is still my favorite and most used. But, I kept the 17-55 for my old 7D. My "second" lens for FF is the 24-70 f2.8L II (and it is a fantastic lens). If your subject matter is similar, consider a long term plan that includes the 70-200. Of course, I've strayed into the land of many presumptions and none of this may apply to your needs.
EDIT:
By the way. Right now, FF or crop, I prefer the 40 f2.8 to any of Canon's current 50's. If I shot poorly lit wedding receptions, then the softness of 50 1.2 is more forgivable. But, the current 50's need to be stopped down close to f2.8 to sharpen up. The 40 is corner-to-corner sharp wide open. Of course, this all depends upon your need, but I'm eagerly waiting for an updated 50 1.4 or 1.2 before spending the dollars on a prime in this focal length.