Well... point #1 was mainly going over how it's hard to refine 'complex' material (i.e.: composites), unless you're only keeping the things that works, which seem to be the Aluminum and carbon nanotubes. Unfortunately, carbon nanotube materials tend to degrade quickly with damage, so it all gets very complicated, especially since you're going all this tricky bonding stuff...
As for #2, well, there were two concerns I was trying to go on. First, this material would be very heavy if you're using any amount of Nerimium. Second, considering that it is ultradense, you'd probably have problems dealing with the ultralight-ultraheavy material meshing.