I know from experience that I don't like breaks or multiple legs on the backside. I can do one and done red-eyes, or even a short leg before the red eye but then I'm a pumpkin. Work out during the sit? Harder than it sounds and I've tried that sort of thing. Fundamental problem is that family men/women will get immediately yanked back to the front side when they finish a trip, so I'm never really in my circadian groove working nights. If you're single might be easier to manage.

In all other respects UPS would obviously be far superior unless maybe you live in an AS PNW base.