Interesting point jonn0
the only lines i can think of are ther hubner variation wich fischer played
and this bizzare line
1.d4..Nf6 2.c4..e6 3..Nc3...Bb4 4.Qc2...b5!? 5.cxb5...a6
6.e3....axb5 7.Bxb5....Bb7 and black has a benko type position however it doesnt look as good for black as the benko
are there any 'initiative seeking' lines in the nimzo(for black)? or is the whole thing more or less positional