So let's slice, say, $15b off of invested capital, taking it from $53b to $38b,

Above is incorrect. You are looking at Total Invested Capital (TIC), but should be looking at Net Invested Capital (NIC).

NIC = TIC - Corporate Borrowings (11.3b) + Net Working Capital (496m) - Preferred Shares (4.375b).

NIC was 37,727 at the end of 3Q, approximately 15 billion less than the 53 billion you used.

and the SOTP comes down to $78.5b, which still leaves the current quote at a 35% discount to conservatively estimated fair value

Adjusting for discrepancy, and leaving everything else the same, the SOTP comes down to 63.5 billion which is a 19% discount to the 50.5 billion market cap at today's close.

I agree with your conclusion that BAM is not overvalued and BN is undervalued, although not as severely.

Buying BAM at 25.60 (5% yield) and below should work out well if the expected 15% annual growth in FRE materializes.

BN is fine as well. Why choose when you can own both! Just decide how much (as a percent of your net worth) you want to allocate to Brookfield, and within that how to split between BN, BAM and the other listed entities if interested.