You are correct in that there are so many variables o contend with. Try to find a reliable combo and stick with it.
I think you are correct. But was that before or after today's standard of FF hoppers?
And That's why I said above that it could still be a nubbin
I am pretty sure TK tested this and found the powerfeed to be just as fast if not faster than vertical feed...so it is a non-issue.