I fly in domestic F all the time because it's the most comfortable seat I can buy but, these are short flights when compared to 12 hours to TYO from the East Coast UA hubs. In addition, I find UA's P+ to have poor padding and a horrible footrest design that just gets in the way, scraping my shins when not deployed and uselessly short when deployed. I avoid P+ on all carriers, not just UA. That being said, I'll fly in any carrier's J lie-flat to save money. In fact, I like the seats with less privacy because I can stretch my legs out more without the very confining foot boxes on the Polaris seats. One of the best for me is the KL A330 with the 2-2-2 J cabin-the bulkhead seats have fantastic legroom.