Hard to say how long the coil heads will last for 2 reasons. First is inconsistency with factory heads. While I haven't had any problems with new heads, some have reported that they have. This is a problem for most manufacturers that hand make coils (like Kanger and Aspire), although the frequency of bad heads seems to have dramatically reduced for both manufacturers lately. But it is possible to get a bad head out of the package. Second, your juice. High VG, high sweetener, and cinnamon juices seem to gunk the coils quicker so you may see less lifespan out of heads than others depending on your juice.
If you are capable of rebuilding heads the Nautilus heads are easily rebuildable. I have a build I really like and I can build from 0.55 ohm up to 2.0 ohm that is rewickable without tearing the head apart. Very easy to work with. So if you like to rebuild, replacement head cost is a moot point really.
One other thing, the new Aerotanks are being released now and early reviews seem to be very positive. So that might be an option to consider too.