I think SLOP should be used on a regular basis, specially on the NATS, but never use the same offset as your colleague above or below, occasional severe turbulence might bring both aircraft mighty close to each other, 1000' is not too much for these TCAS jumpy A/C.

Thanks guys. My original thought though was why not select a truly random offset to the right, for instance 1.7 nm, rather than 0, 1 or 2 nm?

China permits up to 3 miles RIGHT with no ATC clearance required (See Jep manual). But, with their recent implementation (last year) of RVSM, the ATC in China is regularly issuing off-set instructions when more than 2 aircraft within 100 miles of each other (different levels). Most believe there's a bit of a ATC fear factor involved.