This is in relation to the IBM Bluemix talk given at https://www.meetup.com/Toronto-Apache-Spark/events/232329359/ on July 27, 2016.
The main utility being highlighted by IBM folks was their ability to provide fair and efficient allocation for workflows. The key element needed for them to be able to deliver their solution was to be able to be able to schedule at a hierarchy of levels. A thing to note is that Apache Mesos/DCOS allows you to write your own customized allocation modules and/or tune the default hierachical allocator.
I would be interested to see a comparison/benchmark between a properly tuned allocation module (customized hierachical DRF or otherwise) for Mesos with IBM bluemix.