Finally figured out how the "average" boost clock works.
Base: 1006
Boost: 1058
Difference: 52 MHz
Max: 1006 + (52*2) = 1100
The "average" number is just the halfway point in the default power profile. They apparently step the clock at 8 13 MHz intervals, so 1006, 1019, 1032, 1045, 1058, 1071, 1084, 1097, 1110 by default (depending on power consumption). Thus, every 680 will be allowed to clock up to 1100 Mhz by default, it is just how often it does this will depend on the unique power consumption of each board/chip. The clock offset just changes the minimum from which the 8 boost intervals start (which are still power limited).
From what I have gathered, they have been fairly conservative in the profiling, especially regarding power consumption. I'd guess virtually every 680 will easily hit the same clocks as the review samples, though in some cases the user might have to increase the power consumption limit by a small amount. Hopefully, that will rarely be the case though. It will certainly be interesting to see the results from actual users.
Sorry if this has been posted before... haven't been keeping up.