In regards to players with a collection of golden PF reward characters, for gold PF there is no incentive to get top 10% or better if you're trying to farm gold characters. Getting a silver character will get you 4% to a random gold instead of a duplicate which more seasoned players will probably not need or care about. They'll likely already have enough golds to become diamond fodder. If they do have a gold character they want that doesn't come from PF (many!) then it's better for them to get 30% to get a silver for the shards instead of a gold. This is a perverse incentive and does not reward "optimal" play. To combat this, I suggest that gold characters give out 80 shards (or 8%). If this is too much then having gold characters just give out 40 shards -- comparable to a silver -- is likely sufficient.