People leave quite simply because their aspirations change. While TCX are a great company, the pull of a new life in the middle east will attract a number, other operators may offer better command prospects, or a better lifestyle (permenant longhaul/ closer to home). You would expect there to only be a few that will look for pastures new but the mere fact that majors are recruiting seems to make other operators react.
With regards to commuting, my personal belief is that for the 5 months (June-Oct) it will be very difficult. You often have only a few days off in a row, and these can often be impinged on by a night flight prior to. I personally found at Manchester in the summer there was a good number of random leave days, which were available at fairly late notice, and offered a welcome break of 1-3 days.
Hope that helps!