I assume that was directed to me....

Here is the quote from the 1981-1993 MB maintenance manual.
supplement 5 , March 1993. Page 2080/3

" Corrosion protection/antifreeze....

approx 50 percent by volume of antifreeze must be added to the water. The concentration provides antifreeze protection down to approx -37C.
A higher concentration is only practical with even lower ambient temperatures.
Exceeding 55 percent by volume of corrosion protection/antifreeze agent reduces the antifreeze protection as well as the heat dissipating ability of the coolant.
55 percent by volume of corrosion protection/antifreeze agent proves (SIC) antifreeze protection down to approx -45 C.

Checking Coolant in service

...
When refilling after coolant loss ensure that the coolant contains 50 percent by volume of corrosion protection/antifreeze ( protection down to -37C).
... "

The way I read that is that 50 percent antifreeze is the lowest amount recommended.....and 55 percent antifreeze is the highest...

which I wrote as " For long term MB suggests the 50/50 or 45/55 ( water/AF ) partly due to the anticorrosion features.. "

If they changed the recommendation can you point us to the literature ?