1) Yes, that output was just an example of the log format. There are several pages which take 2-3 seconds, but even changing 10.0 to 1 or 0 result in no output.
2)Thank you, I thought as much. However, the command doesn't work any better with the periods escaped:
varnishlog -o -i Backend,RxURL,ReqEnd,RxHeader | perl -ne 'BEGIN { $/= "";} print if (/ReqEnd(?:[\sc]+)\d+\s\d+\.\d+\s+\d+\.\d+\s+\d+\.\d+\s+(\d+\.\d+)/ and $1 > 1.0)'