"or is he going to point out that re-training his 8,000 users onto a new O/S, rebuilding all 8,000 machines,"
If a CIO really believes that is a point of difference then the CIO is a cretin. That is the kind of CEO that is expecting to pay your wages using pots of gold misplaced by hapless Leprechauns.
"The phone-home stuff I don't like, but I can turn most of that off; meanwhile, the update stuff simply isn't going to be enough for me to convince my boss to not upgrade in twelve months"
The unannounced mandatory updates can switch them all back on again, or even add new phone home functionality. Presumably you enjoy playing EULA mandated whack-a-mole in addition to doing your day job. Each to their own I guess. :)