GUEST ED, the examples you give, albeit apparently hallowed by the American Heritage Dictionary, are simply opinions.

Maybe the opinions of a committee.

More probably, the opinions of one person. But opinions nonetheless.

I am afraid that "PhDs", without an apostrophe, "IOUs", without an apostrophe, and "SOSs", without an apostrophe, hit me in the face as being blindingly wrong.

Sorry, but in matters of opinion such as this, I will continue to trust my instincts.

Murray