Show us numbers. That was the main request of my comment, and you come with a list of libraries? We hear all the time how great Scala is with respect to parallel computing. Show me some good examples, where it beats C++ or C# with TPL, say doing number crunching.

It's all to easy to repeat a mantra (parallel programming in Scala rocks), but it has been proven correct rarely. Given such statements, I would either expect it to be much easier to parallelize programs in Scala (as opposed to, say, adding OpenMP pragmas) or would expect parallelized programs to be much faster. Neither seem to be true.