Had the bronze jackpot (Regal or royal, cant remember name) on Jackpot King on Top Cat a few motnhs back for 2.6k with an autopayout when it hit 3k.
Working with what I do i know the seed points and statistical pay points of most jackpots. Not saying I can/will win them, or that I have any more chance, but I know that for example Divine Fortune pays out at around 90k-110k quid for the jackpot. Playing this slot under these JP levels makes your RTP drastically shite.