Any preassignment for such positions is basically wrong. You want a position, there should be a renumeration for it, a big one for certain ungrateful positions.
However, in no case should the other pilots be disadvantaged in their life quality! 
:
Roster advantages are a no go in my view. To enable a selected group more days off in a row, to enable them pre assigned flights does not cut it. It takes away slots for days off of the regular guy, it blocks up to half of the flights to certain home destinations.
Now if some fall back on the rather primitive lines like "if you don't like then leave", or "why don't you join the priviledged ranks", or "we do this as a service to you", then read no further. You have been "Emiratised".
Most of us just want to do a good job and get the renumeration and the days off, a decent roster and the contractual leave.
Is that asking too much?
No, i hate the divide and conquer and i hate the guys jumping on that bandwagon just as much