I agree with John's suggestion regarding the game threshold - five seems to be too many, especially for areas with limited events. Perhaps start the cutoff at three, at which point a newer player would add SOME base value (.1); from there the value would increase slightly for each additional event until they were fully rated (sort of like vesting for a 401k). People in general, whether new to pinball or not, have an innate sense of fairness. I think to deny them all added value until they meet an arbitrary threshold would turn some people off. I understand there are cheaters and those who game the system, but whatever you do, there always will be that element. A fair system strives to satisfy the bulk of its participants, while recognizing that there will be some who will attempt to take advantage of the system. Would it be worthwhile instead to have a feedback system which could serve as a check to this problem instead? A weighted system based on complaints, for example?

Ultimately I think you will need to define a list of acceptable formats, since that will reduce your variables. I can't help but think like a technical troubleshooter (by trade and it's in my blood), and rule #1 is to eliminate random variables. You will make life much easier for many people if IFPA just bites the bullet and adopts a uniform list of accepted formats. Of course, the list can change and grow over time, but if you want to eliminate shenanigans related to gaming formats, it would be a good idea.