I have, and the problem we ran into is not all fish match up. I'm not near my home PC now, but it may be discussed in the newer fishing sticky about gems that you need to know. The current issue is we had theorized certain fish caps (Tianictus) based on this test and the theorized cap is between 110-120 (113 I think to be specific). So, until we can verify that through actually catching 600 and not getting a skill up there are missing variables that halt further testing. However, your theory that it may be a percentage modifier may make sense...