I know the Noctilux is more of a status display item than something anybody would really use. I read that DOF is so shallow that it's hard to focus. It's also quite big and heavy since all the the elements must minimally be as large as the focal length for objects focused at 30x focal length... (f value=focal lenght/lens diameter) and this is for single element lenses...
So, like Heather, I stick to a very old and creaky f/1.8 Nikkor.
And for those who wonder how I know this stuff, I have a book on Optics from Edmund Scientific