I was just noticing that when multiple downloads are pending with "need more sources" and I perform a search that results in available sources, the software immediately sends requests for all the pending items to the new nodes.

This seems a little impolite and puts possibly needless load on the network and nodes. I think that at a minimum, there should be a buffer/delay between sending the requests. It would probably be better if there were some logic involved that would use one item as a test case, and only if appropriate positive responses are received, that the remaining requests would be sent, again with delays/testing.