I think for the way Kraada's workaround would work it would need to be minutes not number of hands, and almost certainly the number of rounds (I assume you mean tournament levels?) won't be possible.
Stars lobby uses 20 hands and PAHud uses 10 hands. For the limit full ring cash games I play, 10 minutes would be about equivalent to PAHud. If you can, make it an option so we can try different settings. The ability to display two averages with different settings would be awesome.