Uplinker
My company specifies on the flight paperwork whether we should SLOP or not. Of course on the day, eg following traffic etc, we can change that but it stops me forgetting to! I seem to recall that NAVCANADA in particular wanted to see a greater number of aircraft on offsets and the system works fine.
Also, we offset on random routes which sometimes follow part of a NAT track say to 30W before peeling off to sunnier climes.
PS we also Offset in the WATRS (Eastern seaboard) airpspace which is RVSM but not MNPS airspace. Must get out more....