I found the site you used to produce the diagrams/formulae and have bookmarked it, but have too much to do to worry about it now. webpage
It may be that these are formulae given to field installers that helps them maximize systems, without needing to do the (likely) much more complex computations, a shorthand of sorts . I say this because the voltage increase of the lower volt panel (in my little experiment) was not proportionate to the increased size and voltage and total watts of the larger panel. To preserve all the watts (or most of them), the voltage increase should have gone closer to 30.
It's all just theoretical at this point, my system is already up with newer matching panels and outproducing the old system, and our discussion has convinced me to match voltages as close as possible in parallel, and amps as close as possible in series as I go forward setting up outlying systems.
Oh, it has also reinforced my idea of many smaller independent controllers and battery banks
speaking of which, I just heard the water filter in my little koi aquarium come on, an independent system I set up with a good controller yesterday. That means the battery voltage is already up to 12.7. Seems like it will be a good day :-)