The miles are a straight-forward non-cash compensation for travelling weekends, evenings and overnights. They are not cash-equivalent as I would certainly not being doing the miles-travel with cash (not in F or J anyway) in absence of my FF benefits. It is a straightforward like-for-like replacement of great discomfort / inconvenience with a somewhat balancing amount of comfort and convenience. I don't travel more because of miles. I do choose certain airlines, but stay within my company's travel policy when doing so, and anyway all the long-haul airlines offer more-or-less-equivalent programmes. Should the company demand I give up my miles I would do so. It would in turn negatively influence my willingness to mess up my evenings, nights and weekends, and I would make that clear to them in return.