My biggest attraction to Linux over VxWorks on these boards is memory protection, so I'm not happy with the first property. There are adequate real time features in the scheduler, as well as scheduler patches, to setup process priorities in similar detail to that available with VxWorks. I'm also starting to play with using a 617 to move data to a commodity PC in lieu of a embedded PPC board. However, it's certainly easier to scale processor horsepower on an external commidity box than on an embedded computer. Anyway, I've been thinking about no-vxworks DAQ systems.
Problem is interrupt latency.