I used Federal 215's in my 300WM, 270WSM reloads since back in 2005. I switched to the GM version as when I went to P & D to buy more reloading supplies along time ago (2007ish), they had no 215's in stock so I loaded up on the Gold Medal Match version. Still use them as I bought a LARGE supply back then.
As mentioned the GM's have tighter manufactured tolerances. Didn't really notice too much of a difference as my reloads shot really tight with the 215's.