Even the first post clearly says the diagram in that link applies to the Pro, please read more carefully:
The thread is but not the first link in that thread it is refering to the cc bec . And no were on CC web site does it say not to run the CC BEC PRO on anything above 6 cells.
That thread is about people that PREFER to run lower voltage's than a 12c set up.
"This PDF show the CC BEC but the drawing is the same if you want to use a CC BEC PRO
with a 12s system but you prefer to run on 6s input."
Of course, Castle will never say we must not use the BEC Pro on 12S after they advertised it as capable of doing so. They are just "recommending" it is for the people who "prefer" to run it on 6S, even if the system is a 12S... It's up to you how you interpret this.
Coincidence or not, the last two posts are about an 8S setup, and a Castle employee recommends powering the BEC Pro from only one of the 2 4S batteries... Your setup is 8S, isn't it? Maybe you should "prefer" to run the BEC Pro on 4S, as that Castle tech "recommends":
"I believe Clint will agree - but I would run it on one of the 4s packs. The lower the input voltage the higher the continuous current will be.