(I created a new account just to keep anonymous on this subject)

How are you guys checking the provably-fair rolls? Because if you are using the Server Seed that the site offers in their History. Then you are doing it wrong.

You need to save the Server Seed Hash that it's going to be used by the server. Copy+Paste on a txt this server seed hash. Then and only then, you can roll. The first thing you need to do when verifying a roll is that the server actually used a seed which has the same hash that you saved.
(Do this on the Free-Game, not the Multiply-BTC)

The math is pristine, yes. But if the server changes the seed that said it was going to use for your next roll, then the whole system falls apart.
Also, the server only needs to do this for the higher prizes. Since you will have to do this around 2500 times to see this behaviour.

The only way you can trust the system is if the server does NOT change the server seed after each roll (that's what Nonces are for). The server only needs to change the seed if you ask the server to provide the seed to you so you can verify the bets. (i.e: Prime-Dice does in fact implement this correctly)

I'm totally ok if the site removes the higher prizes. But if you are going to keep them, at least code a proper provably-fair system implementation.