It would be a great feature, but there are limitations to the data transfer protocol between firewire and USB that inhibit the ability to send real-time audio via this connection. This is something out of the control of PreSonus. There are two PreSonus-approved alternatives to using firewire.
1. Record via thunderbolt using a firewire to thunderbolt adapter from Apple.
2. Record via ethernet over a Dante network connection. This requires an upgrade of the RM using the SL-DANTE-MIX option card.