Depends on the scale/power of attack. The latest hits (happening in the last few months) have been very large and I doubt CloudFlare would be able to successfully defend any of those while maintaining all of the current clients online. I have a client that occasionally gets this kind of blackmailing followed by attacks and they told me they use a US based company specialized in DDoS defending - until now the defense was pretty efficient. I've never bothered to ask for a name, but I guess it's a known one in the "network industry".
You're mistaken. CloudFlare has mitigated many the largest DDoS attacks in history, including some that have exceeded 400Gbps. These recent extortion-based attacks are large, but they are typically 1/10th the volume of the largest attacks we see. For instance, Meetup has publicly stated that they used our network to stop a similar attack. Many of the other recent victims have used CloudFlare as well.
Because of the unique design of our network, I'm unaware of any other service that has as much capacity that can be utilized in aggregate to mitigate large-scale attacks.
