m2eclipse and its extension don't evolve simultaneously. Keeping all in the same p2 mirror on download.jboss.org makes it more difficult to maintain the mirrors, and leads to duplicated stuff.
The repo should be split (so that one mirror mirrors a single source), and target-platform should consume the mutliple mirrors.
For adapters provided by JBoss (wro4j, jdt-compiler...), no need to mirror them.