Jackpots can get people to make bets at the end, when they otherwise would not, so they can keep the game going.
The important things to a good ponzi game, in my opinion, are low fees, a low max bet (1.0 is good), a dedicated forum thread, and not too high of a payout (1.5 is the max I would go, I think). You got all those bases covered.
Too high fees and no one wants to play, just to pay the round owner
Too high of a max bet and someone bets 5, and then people are afraid to get in because it takes too much to pay the 5 guy.
A dedicated forum thread for publicity
too high a payout ratio and the round dies off too fast.
A jackpot or not I think is a minor thing. Some people like 'em, some don't.
This is a good round. And I'm not just saying that because I already got paid.