Not sure if you are interested, but I just had Gconverter convert my Nabble forum that had posts going back to 2008. They migrated over 2000 users, over 8000 posts and over 71k replies for me for a reasonable price. Saved myself a huge headache in trying to migrate that much data.. So glad I found someone to do it.
They did an excellent job – and no I do not work for them 😉