I refuse to change my mind more than once, ever! But this time, there's a reason.Good post, good thinking.
Now, what do you think of Frank's suggestion to start with the 15 and go to the 8? On reflection, I think I like that better than the 12.
I prefer the 12 because (1) margin of error to get on the 8 is larger because I'm coming into the footrail at a flatter angle and (2) whether I try to do this off the 8 ball right away or off the 5 ball bank, I have both the 10 and 15 available to get an ideal angle on. Also, starting with the 15 leaves a risk down the line of screwing up and having to shoot the 10-12 combo. Even if not, the 12 and 10 do not lay as naturally for getting both easily.
I also don't see the 12 ball as any harder than the 15. On the other hand, if you never miss a spot shot then, well, the 15 is a spot shot.
P.S. Can I sit next to the short bus driver for a little while now?