Hi Bernd,
if you are mainly interested in the data exchanged with the partner, you can 'or' the trace level with the flag ParameterData, e.g..you want to see level 2 trace plus the function data: RfcTracing.Level2|RfcTracing.ParameterData. When not doing it programmatically, but using app.config for setting the trace level you specify 2|ParameterData in the respective value for trace (general or destination specific).
Best regards,
Markus