Coming from someone who co-owns a site that offers house bankroll contributions (Moneypot.com), unless you have a worked out deal, know the owners personally and/or are able to easily connect to them and have their personal details, you should be diversifying between a few sites to minimize variance and risk of ruin.
That's really scary to think that you, as a co-owner of a casino that receives investments, is thinking that there is a great chance that there would be some owners that will run away with the money of the investors. You are technically saying, "diversify, because we don't know if they will run for the money!" Which I hope the casino owners don't do.
I did not say that. I don't think there is a great chance, but the chance always exists. Please let me clarify more.
First, let me state, that I have some of my own personal funds diversified through quite a few sites that offer investments. The amount differs by how much I trust them, how much I know about the owners, past history, reputation, stake of bankroll ratio, betting volume to bankroll ratio, and a few other things.
I am confident that in the long run, it will provide me with a lucrative return.
Now having said that, there is always a chance owners (albeit imo, a very small chance with most of the top sites these days) will run away with investor's money.
That's why it pays to research, reach out to owners, talk with them and establish a direct line of contact if possible. Find out what the best and worst case scenarios are. Find out what happens if they do disappear for example and if there's something to track them down or just an empty shell company or completely anonymous information.
That isn't the only reason to diversify though. You want to minimize variance and volatility so that your risk of ruin is lowered. For instance (this is not an attack on SD), if you had all your bitcoin invested into safedice, there was a period where you could have lost 90% of your holdings in one night. If you're looking to invest and grow, your aim should be to make it to the long run instead of gambling against whales and heavy action.