I just read Jan Heine's review in the new Bicycle Quarterly and believe he was comparing the 1980s heat treated 0.7/0.4/.07 Prestige to the 2013 0.8/0.5/0.8 Prestige that's not heat treated. While they're clearly different, I think it would be very difficult for even the most experienced riders to tell the difference in ride quality between the two tubesets. The difference in tensile strength from heat treating and the tenth of a millimeter in wall thickness would make in the ride quality would be insignificant.

I'm guessing the reason SOMA used the non heat treated Prestige rather than the heat treated Prestige JPN is because the Grand Randonneur is TIG welded, and the heat from welding (as opposed to the heat from low temperature silver brazing with lugs) would weaken the heat treated thinner walled Prestige JPN.