Some months ago I added statistics logging to Pi Presents Gapless.
There is a new section of the manual which should explain all.
The logging outputs a Excel/Calc compatible CSV file which contains details of user initiated events. The file can be analysed to obtain the statistics.
I do not have any deployed applications from which I could collect statistics so I cannot assess whether the messages PP outputs are sufficient in content, and in the events that are recorded, to produce useful tables; so feedback would be useful if you fancy trying it out.