2% riskless (or with a real low risk to be more precise) is far from being nothing. Tell me what other method can bring you a 25% "guaranteed" annual profit and I give you the management of an edge found....
The arrival of short sells possibilities on some bitcoins/altcoins platforms is a real opportunity to make easy profit with arbitrage (which is pretty much impossible on traditional forex now, unless you take a high leverage and/or trade really high volumes, with the associated risks if anything goes wrong...)
I am planning on making a program similar to blackbird but in java (java has many advantages over C++ for this kind of application I think. Appart from the fact that I am more comfortable with coding in java , java also has many bitcoins/altcoins related libs already implemented (like https://github.com/timmolter/XChange), which should ease the development and maintenance of the program. Also, java can easily be multi-threaded (important to make simultaneous api requests on all platforms) and run on pretty much any platform. Finaly, making a UI in java is really easier than in C++. As for the "performances" concern, I can tell you that java can be more efficient than C++ in many cases (anyway performance must not be an issue in this use case where there is no computational intensive tasks. So any language would fit here...))
I don't know if anyone would be interested into helping and I haven't decided if I would make it open source or not yet (would mainly depends whether other people want to contribute or not) but if you are interested to join, you can send me a PM.