Ok so how exactly does SLOP benefit?
1. With regard to wake turbulence, yes it is a big help.
2. With regard to avoiding potential collisions I simply don't see how this really plays out over the Atlantic. If you're on the OTS then opposite direction traffic simply isn't a factor. As for random routes they are chosen to take advantage of or to minimize effect of wind. Therefore flying the same route in the opposite direction is the worst possible choice.
I feel SLOP would be far more advantageous on traditional bidirectional airways. But then again how many times have planes collided head on on the same airway?