"So if that figure [$493K-$498K] were known and published now, the current price would be around 1.443 - 1.457 times book? That's below my estimate of the highest multiple paid for shares repurchased seemingly for purely economic reasons, which in my view seems to top out in the 1.46-1.48 region for B shares."

So by this math, which I agree with, Berkshire should repurchase shares now, or after the Q4 report. Why hold so much in T-Bills yielding 3.6% when you can buy a company that you know intimately, which is 5% undervalued and which will probably return 5+ percentage points more than the T-Bills? I would not make the same argument for buying any other company, but with BRK.B there no skeletons in the closet that management is unaware of.