I needed some alternative for Sportsbet to find better odds and sport events not available there, so I will be testing Rollbit in next few weeks to see how everything works.
Rollbit does have better odds in some markets sometimes when compared to Sportsbet though they don't offer lucrative boosts in various sports on a regular basis. Heard of people getting limited quickly too though I am not sure about this.
I don't think you will find many new markets in Rollbit when compared to Sportsbet based on what I observed.