Pretty sure that coinroll is legit and is paying out. Probably just some minor flaws in the system currently, and will be fixed.
Also, it was just you who is not getting your withdrawal. Personally i have already received one withdrawal, and I have gambled on their site a few times as well, withdrew a total of 0.6+ coins. I don't think they're scams at all. In fact if they really wanted to scam they wouldn't scam you. Rather they'd either would rig the rolls or simply run away with depositors money. The whole point of a sig campaign is to get positive exposure.
I have chatted with Namworld on skype and he is very supportive and responsible. I suggest you do so as well.
Me too not receiving any payment since about 3 weeks, so not only OP have this problem, and if you check the signature thread you will see that a lot of the campaign's participants told that they aren't receiving their pending withdrawals since weeks till now, as well.
In addition Namworld don't respond in the official thread nor in PM, and it's very bad sign.