I've been tempted by the 50 1.2 for a long time, but never get around to it with so many cheap 1.4 options showing up on my doorstep. Incredible that it is still available new.
BTW, I haven't been into versions beyond AI but Nikkor lenses are pretty easy to work on. Your smudge will probably clean up just fine and I doubt you would have to spend much money if you don't want to do it yourself. Or trade it to a DIY'er since these don't go for all that much $. I don't need it, and kind of lean toward the older lenses anyway, or I'd be PM'ing to try and trade you out of it.
Enjoy the Micro. I was late discovering these, but they are wonderful lenses where the aperture is adequate.