Real-world 2 site DPM 2010 and Firestreamer solution
Posted: 28 Apr 2011, 08:18
Cristalink guarantees that Firestreamer will perform "substantially in accordance with the written materials that accompany Firestreamer", see EULA. If it can comfort you, Cristalink is listed as a DPM Solutions Services Partner on microsoft.com.
As to the scenario that you described (DPM2 protecting DPM1), you should forward your question to Microsoft Support or an appropriate DPM-specific forum, for example, System Center Data Protection Manager Forums (you may also want to search for "Firestreamer" there). See also Backing Up DPM by Using a Secondary DPM Server.