I have to say the level of FUD in this thread is amazing.
One way to find out what is being sent to Piriform (Avast) is to run a Wireshark trace and examine the packets.
Most would rather just repeat the FUD rather than try to actually prove their claims.
I personally have found no evidence of personal information being sent by CCleaner.
If anyone has, I would be interested in seeing it.
BTW, gathering metrics is not new. Lots of software these days gather metrics, including antivirus and anti-malware programs.
If it bothers you, simply add a firewall rule to block CCleaner from making outgoing connections.