Pretty cool. I've never really had a problem just implementing curl_multi, but if I need to do something with parallel requests in PHP I'll definitely check this out.
MCS, I liked this for the back end in prep to resolve migration of two huge construction company databases. Curl is like a ghost but its stability to hold both patterns is pretty cool for dual extraction methods. It works better as a seam between two existing sources rather than a compliment to any new gear.