Hi Marco,
I would suggest you to have a look at the enhancement request CSCtd11613.
Currently, rate is the average rate from the time the TCP session for RDRs is establish and peak is the peak rate in the past execution of this CLU, including current execution.
This is not very useful, the rate should cover a shorter period than the duration of the established connection and peak should not be related to previous use of the CLU. This is what CSCtd11613 wants to address.
"rdr-rate.py" is giving a more interesting output on the CM or "show RDR-formatter statistics" on each SCE.
Cheers,
Tom