I think one reason why people on this thread are disagreeing, and perhaps outside of this thread as well, is that people are defining 'most of the dancing' in different ways.
To some people, NP did 'most of the dancing' as when you look at the dancing shots in the movie, the vast majority are of her (either waist up shots, full body on the not insanely hard stuff, or full body with modified steps), and only a minority are Lane (feet only, full body with NP's face superimposed).
Other people are looking at the dancing that must be done throughout this filming, without relation to the shot lengths/types themselves, and noting that Lane *must* have done a significant amount of the dancing in order to actually *get* all the shots.
Further exacerbating that problem might be which shots people consider part of the 'dancing'. If one is, for instance, including absolutely everything that could possibly be remotely characterized as dancing (where other people might say, that's just a shot of her holding her arms in position), the balance tips in NP's favor. If you go the other extreme and only characterize as 'dancing' the actual full on dance sequence shots, the balance may well tip more toward Lane.
I honestly think some semantic differences are underpinning a significant amount of this controversy.