My apologies for misstating some of the numbers. My upper legs are quite short, so even cramped seats are fine for me and I do tend to overestimate seat pitch.

As for Acela FC seats being 2" wider, that honestly is news to me. I have not found the difference to be discernible, possibly because a 21" width is already quite generous as it is. This might make a difference to a larger person.

Guess I should stick to the anecdotes and avoid numerical guesstimations from now on!