Hi Carlos,
I finally came around testing the functionality. It helped us already find a solution to our initial problem. Therefore, I think you should include the possibility to specify the user in the standard version of ANST.
However, I'd have an additional suggestion. It should also be possible to specify for which function module or method a trace for a user should be written. Basically similar to what is possible when scheduling SAT traces. The reason is that there are usually quite a number of RFCs going back and forth between SAP CRM and IS-U. Limiting the scope of the trace would make it a lot easier to really trace the area one is interested in.
Best,
Christian