Primedice would be best if they accepted investors
They prefer keeping 100% of the profit for themselves and have a big enough bankroll to offer a max profit of 40 BTC per roll.
it's 20 BTC now that is also not bad
PD decreased max profit after some guy won 2000 BTC
That's the advantage of sites with crowd funded bankroll, they can offer higher max profit, if someone wins big - the investors get hit. PRC has max profit of ~135 BTC and it keeps growing.
It's good for investors as it attracts big players, and if they want to reduce the risk, they can choose low kelly option (1/4 or 1/2).