Can a Finney Attack make SatoshiDice betting profitable? If you perform a Finney Attack whenever your bet fails (by replacing it with a transaction to yourself), then would it make betting profitable, even though the Finney attack won't always work? How much mining power would you need to break even on profitability?
The short answer is: yes, but it would not be profitable in the long-term.
A Finney Attack is not easy to pull off, because guessing when the rogue miner's block will be generated is imprecise and inaccurate. Guessing gets easier with the more hashing power the rogue miner puts on the network, but you probably won't see real profit unless you get a pool to participate in your attack.