"Do you actually leverage HDFS and the Hadoop scheduling infrastructure to run ParallelX jobs?" -- Yes.

We could also provide what you're suggesting outside of Hadoop, no problem!

"What are the limits like for input data sizes?" --- There are no limits. You can store your data in AWS, and we will crunch it for you. That said, initially, for IO-bound and disk-bound jobs, ParallelX might not be ideal. This is a problem we are solving as we scale.

Thanks for the feedback! We appreciate it!