it begs the question then, what video card and computer you using, without being funny, i could understand the time taken if it an older machine or something but this time is not a good advert for Maxwell (by all accounts). I think most here find it hard enough to sit through a 60 minute render much less a 60 hour one. the work is great as already mentioned many times, but i think you could be working on Maya rather than waiting nearly 3 days for a render, but, you must like it very much. Mental ray is not that hard if you get a tut, really, if i can follow it anyone can. the quality is as good i think as this, if you like render, you should be intrigued by MR.
but, onward all good men...
take it easy and life will be easy