Thank you everyone for your responses. Much appreciated.
I'm aware of Roger C.'s 3-part series on AF systems and lenses. What a wonderful set of reads. What I found most intriguing was the variance in AF consistency between lenses tested, irrespective of newer 'closed loop' sensors. From the set he tested, the zoom with the lowest deviation shot-to-shot was the 70-300L.
See here: http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-3a-canon-lenses
FoCal's AF Consistency test's ability to evaluate 'x' number of shots using a range of 'y to z' AFMA values though would make one presume there is a difference in the precision (repeat-ability) of shot-to-shot AFMA values for a given body/lens combination.
I have seen it first-hand using that test. Unless FoCal is lying, there does appear to be a correlation. I can find some of my saved PDF test reports and post them.
Not disputing others' experiences. I am but a 9-year intermediate user of these technologies so not an expert by any means, but there are clearly so many unknown and undocumented variables that folks like Roger and others end up having to deduce/prove, that one has to wonder if AFMA behaves differently with 'older gen' lenses than the 'next/newer gen' barrels.
Since in an older generation lens there is no 'confirmation' back to the camera that the lens did, in fact step-move only 'x' points forward or backward, one has to wonder.
I know my first-hand experience with my 70-200 2.8 non-IS (which I still own before I picked up the 70-200 2.8 IS II recently) was shot-to-shot variability and after Canon calibrated it, not only was it just about perfect at AFMA zero, shot-to-shot precision (repeat-ability) significantly improved, so much so, it's as good as my IS II is.