The only ChinaBU nodes are living on centralized server instances, and none are actually used for bitcoin commerce. The software is unsafe. No exchange, wallet, payment processor, or user, would dare dream of using it. Which is why hundreds can disappear in the space of an hour, and re-appear 12 hours later all at once.

But to clear it up, there are thousands of nodes. By some measures, when including non-listening nodes, 10's of thousands.