Rob, these are the first 5 sets I rolled with that method:
11, 12, 12, 14, 15, 16 = 80, or 35pt
12, 15, 15, 16, 17, 17 = 92, or 50pt
13, 13, 17, 17, 18, 18 = 96, or 68pt
14, 14, 15, 16, 16, 16 = 91, or 50pt
12, 14, 14, 15, 15, 18 = 88, or 48pt
Though my sample may be small, your method seems to give an average of 90 or so flat ability points, or somewhere around 50 points according to the point buy system. That's VERY high compared to the usual 32 point system.
Also, the points seem better distributed, with 12 or 13 being the usual lowest number and 16 or 17 being the highest.
Not a bad system for creating a mix of character power levels on the very high end of the usual power scale.