Yes, I agree that Ah and power drain has everything to do with Amp draw BUT the idea of coming up with an accurate comparison of two batteries based on average draw is more of a guess than an equation. The draw on the battery changes constantly based on so many factors including initial startup, heat in wires, terrain, riders weight and the list goes on.
The only thing that has changed is the batteries capacity therefore the only direct answer is percentage of capacity. Your first post used a 30Ah average draw. That would mean a 24 min runtime on a 12 Ah battery, add 2 Ah capacity and you add 4 min. runtime. This is not very accurate because a BPRO's should not come close to a 30 amp average draw but the idea of a monetary 30 amp draw is realistic. It also leads one to believe a 2 Ah increase will only give a 4-5 min runtime increase. In real world it should be somewhere between 6 to 12 minutes.
I’m just saying, there is absolutely no need to try to determine the very inconsistent and difficult to measure average amp draw just to get back to Ah.
Use the easy to measure, original runtime and the known Ah ratings = accurate comparisons.