Hah! ... <Aliens>It's a bug hunt!!</Aliens> Strange (to me) that RAM-limits could be so vague at the design/execution stages--in 2013.

'X' (with the most posting chops) appears to fall-back on vague suppositions + (an opinion that) 'Apple doesn't arbitrarily limit max memory') while mostly ignoring the L-->Snow Leopard effects throughout the thread.

OWC rep appears to be the most competent there: having deduced a testing means which works--all, of course re the MBPs. But they are (were? haven't checked lately) correct re 8 vs 6 GB on my model iMac.
Guess I'll drop in at OWC and see if their now codified Go/No-GO tests have revealed any combo for 8 GB ..sans kernel panic.

They seem.. to be ahead of Apple re this particular MBP model. But that was 4 years ago.
Will chime in if they Have a new option for me. Unlikely, but this-all gives a view of there being too much magick in the analyses--from Apple more than OWC! [Now it's 4 years later.. are they any better?]

Well, the thread was at least as good as a NYTimes Saturday X-word :-) Thanks again for finding such a relevant example.