I've experimented quite a bit with saddle setback over the last year since I got my Kickr Bike - as it's easy to change very quickly.
I've tried Steve Hogg's balance method (which appears to be quite popular among UK fitters), but that didn't really nail it down to any specific position i.e. I feel "balanced" anywhere over at least a 50 mm range. So while I like the concept, ultimately I didn't find it all that useful in setting a specific saddle setback.
What I have found is that if I go too far rearward (saddle height and reach corrected) then my pedal stroke feels more laboured. I find spinning a relatively high cadence with power easier and more natural with a relatively forward position. This reminds me that I haven't actually found my limit yet on moving the saddle forward. I still have plenty of scope to move at least another 10-15 mm on the rails. This is all relative. My saddle setback is still quite rearward compared to the current race trend of zero setback posts and saddles slammed forward.
I can't really comment much on your proposed formula. It sounds tricky to measure and I'm not convinced it's going to give a "Universal" answer. There was a long thread somewhere on another forum (more race-oriented) discussing how much saddle setback riders actually use. They were all over the place, with no obvious pattern. Although measuring setback from saddle nose across a wide-range of saddles is not going to be apples vs apples. The OP tried to get people to measure setback relative to their sit-bone contact point, rather than saddle nose, but you can imagine the response.
So my thoughts are that a formula may not be applicable to saddle setback. Maybe it's just one of those things that requires individual trial and error. From my own experience it isn't a particularly sensitive parameter for me anyway. For me it's very much second order to saddle height and it's hard enough coming up with a "Universal" formula for that.