A cynical hypothesis on the "30- mile lateral" vs 1,000' RVSM- (I believe) there are ususally 5 NAT tracks, identified A-E so if you reduce separation laterally to 1/2 a degree of latitude you would add an extra 4 tracks. By introducing RVSM between FLs 290 & 430 you add 7 FLs, or 7 new "tracks" (or have I got the vertical dimensions for RVSM embarrassingly wrong?).