I spoke to one of the guys at Nebula, and he said this about using the Cuda dsp card:
About cuda: we stopped every other developement for it. We started 3 days ago. As promised, the developement takes just few days: the \"nebula cuda wrapper\" is already working. Tomorrow I'll tell you if the Nvidia SDK release is enough stable or not! But if it isn't, don't worry, it's just a matter of time (Cuda is actually a beta release).