rhysiam :
I actually have a WD green drive with my games on it. Wasn't my first choice, but I already have an SSD for OS and someone gave me the drive for free, made it hard to justify the extra expense of a 7200RPM drive.
While it's fine, it doesn't have any affect in-game, load times are substantial. I've noticed that loads in games like XCom2 and Witcher 3 take a long, long time. If I was starting fresh the blue would for-sure be worth the extra few dollars IMHO. But if you already have a green it will work.
My daughter runs off a Green as her Steam drive (SSD O/S) - I've moved from WD Black, to SSD and finally to a remote 4-drive NAS for my Steam drive over the last few weeks - I've never seen her load times on the games we MP together (Far Cry3, TF2, CS:GO, L4D2, Broforce - but I doubt that one counts
) to be any different to mine - it was her Green vs my Black load time similarities that started me testing load times on various platforms.