To me, it would somewhat depend on what fixtures were there in the apartment. If it is just a shower and say a kitchen, and only a shower, not a tub, a tankless could work fine. Hassle is the required maintenance (periodic deliming). Depending on your water coming in, that could be fairly frequent. If you have a softener, probably not very often.
What are you doing for heat in the apartment?
If it's just that it takes too long to get hot water there, why not just put in a recirculation system? To save some, insulate the lines, and run it on a timer.