For what it's worth, I think the extra tier points make it almost worth suffering in what is essential a WTP seat without the foot rest for 4.5-6 hour flights.

It would not surprise me if, at some point, the US carriers change domestic first class to be business class on two-class aircraft. I assume the main reason they do it today is to make it easier for passengers booking on international F tickets to include a connecting ticket in F.

I did a quick look at my past year of flying, and I had roughly the same number of segments on BA and AA (a few more on BA), and the cost per tier point was roughly the same between the two carriers. I earned a bit more than double the number of tier points on AA as I did on BA, but also spent about a bit more than double with AA.

I think we're quick to see the tier point runs or advance purchase F fares, but a more typical pattern for me at least is "I need to be on the east coast in next week", which can be up to $2500 for a return ticket for say PHX-JFK, though you'll often struggle to find availability in F on short notice.