"I got 1.47x trailing for that Nov '23 repurchase"

If I had to guess Buffett's estimate of IV based on stock repurchases, I'd go with his highest (not average) P/BV paid. These were the purchases in April, 2024 when he paid 1.601x March 31 BV, or 1.567x June 30 BV. On Sept 1, 2024 Berkshire actually issued B-shares as part of a larger transaction at $456.7 per share, or 1.636x June 30 BV, or 1.565x Sept 30 BV. If Buffett is issuing stock at 1.565x quarter-end BV and repurchasing stock at 1.567x quarter-end BV, then his estimate of IV must be pretty close to 1.565x quarter-end BV, or about 1.527x beginning BV for the quarter.

I've never really bought in to the argument that we should dismiss repurchases which were private transactions or where no B-shares were repurchased (2023 and 2024). None of us can read Buffett's mind, but my guess is that he doesn't veer very far from his estimate of IV.