I would get leatherette...considering I have had BOTH in my car, leather is far superior in terms of BREATHING. Leatherette doesn't breath as well as leather, so when its hot/cold it keeps that temperature for longer. Even in hot murky days, the leather seats dont get too hot.
Down the road, leatherette will rip and tear, leather will crack. I would personally recommend leather, its just a better and more luxurious option to have. After having leatherette in my car for 6 months, and then leather for the next 4, this is my take on it
It feels like a louis vuitton bag haha (leatherette that is).
Also, you can't get M-sport with a heated wheel as far as i know. The m-sport perforated wheel doesnt come with a heating option.
Thirdly, I was given 6% off on my finance....generally you should be able to get at least 4% if you really bargain 'em down.