Hi.
I believe it would be very useful to provide a way to compare 2 traces.
It could be done in a textual way (a la "diff", the unix way), or graphically (I personally like very much kompare[1] output).
Bonus points for providing a way to diff once filters have been applied (so one could compare only exchanges for a given endpoint from 2 traces, for example).
[1] http://www.caffeinated.me.uk/kompare/