As a rule of thumb I will look for cheap ex-EU when travelling East from the UK (usually QR), and use a 2-4-1 for travelling West (recent uses include GRU/GIG, MEX, JFK and IAD/IAH). I also attribute a "value" to being able to fly direct from London as compared with positioning flights and accomodation (which I factor into the cost of an ex-EU course).

It's far from worthless to me, but as noted this is all quite subjective.