I agree with most above.
The only blad pissing war's were over
80mm and 100mm being that much better and so similar a focal length.
and the 180 was known as better than the 150... the 150 has always served me just fine though.
TODAY buying used!!!! I would be more concerned with weather it was taken apart and re-assembled by a professional that lives up to the professional standards. The lenses come apart similar to view camera lenses paper thin tolerances are required to return to factory spec.