Just a note on your color variance, understand I am not familiar with dies, only 2 step tin coloring.
Voltage as you said will play a vital role. Anodized coatings at 10 volts will give you a smaller pore structure but will be more porous, but an anodized coating at 20 volts will be less porous but will have a larger pore diameter.
We have found that anodizing no greater than 12 amps/sq.ft. will give us the best color uniformity depending on load size. If amp rating on our rectifier is maxed we may run at 18 volts for best color uniformity and adjust our anodize time to the running amps.
Acid concentration, temperature, air agitation and aluminum content can all play a role in the voltage.
Voltage will control the pore volume, while the current as a function of time will control film thickness.
As for your mill thickness issue, we use mill meters that we buy from the Paul Gardner Company or Defalsco. Very easy to use but kind of pricey. (Up to $900.00)
If your using the 720 rule and all of your anodize parameters are inline, ie: Acid Concentration, aluminum content, temperature, cathode ratio and proper amps/sq.ft. you would have to be very close to the mill spec you are trying to acheive. This will very depending on alloys but should be very close.
I am also very impressed by your reseach you shared.
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