Here's the description of Musa nagensium-
Musa nagensium
Now the description of Musa cheesmani-
Musa cheesmani
From those descriptions it seems like the nagensium isn't in cultivation, and the seeds being sold as Musa nagesium are actually Musa cheesmani.
As far as I know none of the seeds sold as Musa nagensium turned out looking like this awesome plant-
Musa nagensium images
Trebrown did import some seeds of a really dark stemmed plant from the area that nagensium grows, but it may have just been another cheesmani, did anyone order any of those seeds and get a sprout or two. It would be pretty easy to tell if it was different than the other ones, because the leafs are so distinct even at an early stage.
Here's a thread on Trebrown, but it seems a jumble of mix up since my M.auranticana from him doesn't have leaves like that at all.
http://www.trebrown.com/forum/viewtopic.php?t=302