dd should be able to suppress printing status information
From GNU dd manpage:
‘status=which’ Transfer information is normally output to stderr upon receipt of the ‘INFO’ signal or when dd exits. Specifying which will identify which information to suppress. ‘noxfer’ Do not print the transfer rate and volume statistics that normally make up the last status line. ‘none’ Do not print any informational or warning messages to stderr. Error messages are output as normal.
illumos dd should support this as well.