Generally, I see exports use the sys_updated_on to perform incremental updates. Since there is no time stamp on the l1 and l2 tables, how will you export the data out? You can use starts_on, but be careful since a historical collection won't be obvious (or possibly detectable from the pa_scores_l1 table alone). You will most likely need to bring over all the supporting pa tables as well. Essentially, you'll be recreating the Performance Analytics API and the widgets on your own to get what Performance Analytics produces in the platform. Be ready for lots of questions from your users as you will have to put in a lot of work to ensure the data reflects what you think it should be.
This is not a recommended approach.
