Sheldon Brown only cites the possibility of a blowout, and only "if you feel like taking the trouble." I get the impression that he is almost as lukewarm about it as I am.

Just to be argumentative, excluding replacement-required scenarios like sidewall cuts and wear in the the casing, is there any objective reason to expect the more used tire to be more prone to blowouts than the new one? Does SB have anything to say about blowouts, other than bad tubes and badly damaged tires? Still talking about rotating the still-good tire back, just to have the new one on front.