Of course it will be nice to have bitcointalk users only as the participants, maybe you'll get different luck by having more participants than other casinos that tried it here.
Probably not but hey every site needs to start at ground zero and starting a decent bitcointalk exclusive contest is definitely one of the way.
Most of the time I saw the winner was Panjul07 and Mahdirakib. There are a few more regular players. But, I don't think there are more than 20 players who participate in contest regularly. So, seeing the same winner over and over is not impossible.
well I mean, some user are good at specific contest though. I've seen some user that actually won decent amount of times in slot related contest. Some won in sports predictions contest for quite some time and I myself have won 3 times in a row in poker contest in this forum so yeah when we get pretty much similar winners over time, people got bored because they cant win a piece of the prizes