A good measuring stick is if your total hashrate is faster than 40-50% of miners.
With 40-50% of Global Hashrate (-NetHash), there is no other option than solo mining. I mean solo mining will be (more..more) better than pooled mining. More than that, we can do 51% attach, right?
But it's not our guarantee to making a good profit, and it will depend on the amount of block reward and coin prices (-if this coin has listed on the market) comparing to the operational cost. (-if the context is "profit")