As a non-oceanic controller it does seem strange to me that separation in the vertical can be reduced by 50% to 1000 feet, but the lateral still remains at 60 miles or 10 minutes in trail which is about 80 miles.
I know its a procedural environment and commnication is difficult but surely modern aircraft are more likely to deviate vertically than laterally.
Have any studies been carried out on the advantages of reducing the lateral (track) separation by 50% to 30 miles (an awful long way even allowing for offsets)?
You could use the RVSM produced levels (300, 320, 340 etc) on the intermediate tracks so that vertical separation on the same track became 2000 feet again.
Just a thought...