> The speeds were just stunning to say the least at 15GB/s.

That is amazing. That is around DDR4-1866 speeds, and not far from DDR4-2666 (~21 GB/s). At those speeds I would happily work with dataframes sitting on the disk rather than in memory [1, 2]. Did you benchmark RAID 0 with less than four disks?

[1] R: https://github.com/xiaodaigh/disk.frame

[2] Python: https://docs.dask.org/en/latest/dataframe.html