I can comment on my LSD2 comparred to the akg c422 I used to run. I knew that mics sound and performance very well and have a lot of recordings to reference.
while the AKG is no doube a nicer mic in both fit, finish and function. the silly LSD compares very favorably, imo.
In fact, I prefer the LSD2 recordings ive made. Once you factor in the price...its an easy decision.
the AKG is a little smoother and more refined sounding, but the LSD has incredible soundstage and off axis performance. Detail is top notch as well.
now, the 426b I would expect to sound better than the 422, as they progressed with each new model.
Can't comment on the neumann, but I love neumann LDs, so I'm sure it sounds great.