I did exactly what you are doing in 2000 for a two year stint in Dubai. I signed up for Emirates Skyward and it provided a lot of convenient perks at the airport that you will not get any other way. Remember that you will likely also take some vacation flights when in Dubai since so many great locations are nearby. this could easily take you over the 50k level.

The one major caveat is, as already noted, the EK miles expire three eyars after you earn them. Make sure you use them before you demob from Dubai (or have a relative/ good friend to give them to, whihc is what I did.)

Glenn