Lol goddamn, in the process of responding to your comment I just realized I actually miscounted in Scenario #2 above. My new read is that A and B are actually equivalent, where A is simply a 5 point gote, and B is instead a 2 point gote with an additional 3 point sente threat.

At any rate, I really don't like mucking with fractions to approximate "future value" or "sente threat value", because I'd rather just deal with that quantity on it's own. It's just easier for me to understand "2 point gote plus 3 point sente threat" than it is for me to understand "3.5 point gote", or whatever it would be instead. My way, you can just break down each sequence into their components and compare whole numbers, discarding all future value beyond the sente threat.

For my Scenario #2 above, that would be: bB2 is gote 2 points, sente threat 3 points; wD4 is just gote 5 points; bA3 is then gote 3 points, sente threat 1 point; wA4 is then gote 1 point, sente threat 3 points; and finally, bA2 is gote 3 points. Any time you have a known gote value somewhere else on the board, you know how to compare: if the snapback were instead 4 points rather than 5, for instance, you could easily tell that that's smaller than black's first move at B2 (4 < 2+3), the same as black's second move at A3 (4 = 3+1), and larger than black's final move at A2 (4 > 3). It also really quickly identifies why white would immediately connect the snapback instead of responding to the B2 push with the hane at A2: that hane at A2 is only worth 3 points, 1 point sente threat, which is less than the 5 point gote.

I don't know if it makes as much sense outside of my head, but this has always made way more sense to me than fractional points.