OP, I recommend you could find your bugs and vulnerables by yourselves, not rely on players losses here. I want to bet on your site, but now I think you may confiscate my fund, why? You claim most bets are double-spends, do you know the current bitcoin network is very slow? And people wait one transaction with 24 hours even they have paid 0.0005 btc, if you use double-spend as an EXCUSE to non-payment, you will lose all customers very soon.
He doesn't call all transaction that don't confirm as double spends, only the ones with VERY small miner fees or the ones who a few seconds after the initial transaction, another one is made using the same input to another address with a higher fee.
These days its not smart to run any type of gaming site which is anonymous like this because you bet by a bitcoin transaction because the double spend is a huge issue and very easy for many to perform.
The bigger issue with this site is how almost all the bets are pretty much getting delayed because they require manual approval to release payment and that makes it very hectik for most since the website doesnt have any form of support and users are required to make a new account on Bitcointalk just to get their BTC back.
I hope OP will update his system which is against double spends, otherwise the business is not easy, and many scam accusations. I don't know why this situation is always happening.