In other words, IPH should play a much bigger role in the rivals list algorithm. I'd even say CRUCIAL roll.
p.s. I also agree that the prizes should get better with each upgrade. Especially considering the price for the last few upgrades. With that said, i can't understand why gree limits these LTBs to 18 days. Even if you give 21 days, 99% of the players would not be able to get it to 10 in time.