I am not interested in sampling, the problem is that libraries required to log data can not be salted with enough yields() to get low jitter or worse, missed data points. You don't need a scheduler to sample at 500 Hz, it's trivial.
You must learn something about the theory of SNR for ADC sampling. Data is worthless if there is substantial jitter in the time between data points.
Your toy examples don't proving anything. You must do real examples with popular Arduino libraries. That's why I include a real data logging example.
but for Teensy3 and Arduino DUE, the size of the program memory might not be ok
I didn't mean running a true Linux/Unix I meant one of the many small kernels that are Linux like. These kernels run on very small processors. There are an amazing number of kernels out there.
I still beleive that we have nice days ahead of us with Schedulers
Your right, there are still lots people writing coop schedulers so you are not the last diehard. People still write apps in assembler too.