The song length may not be identical, but the track may still be able to be used. For instance, if I rip a track from a CD, it might be one length, but the same track downloaded from Amazon might be slightly different. If they add blank space to the front or end of the track, that doesn't change the actual beat, just when it starts in the MP3.
I have a sequence like that. I have the music from a CD, but it is slightly different from the sequence I downloaded and does not line up well at all as downloaded. If I add or delete cells to/from the beginning of the sequence, it shifts the beat track to line up with my version of the song. So as long as the songs are the same versions, they should be able to be lined up and shared. it might just take shifting the track to match your specific music file.
Also, nutcracker uses "chunks" of the music. So a section could start @ 10.4 seconds and end @ 24.6 seconds. So a nutcracker effect would play during that time, but there are many beats during that 14.2 seconds that are not accounted for...especially if you are using other DMX items that activate to the beat or melody of the song. You might get an effect to be close to the beat, but there will be no substituting for manually lining up your lights with a good beat track in areas where you need that kind of precision. Each type of sequencing has their place and are used extensively in each of my songs.
My $0.02,
-Keith