Jeff,
From throughput point of view, I do not see much difference between transfer queues in EDMA0 and EDMA1 with the same DBS.
For the bus latency point of view, please take a look at Chapter 4 System Interconnect in C6678 data manual. The EDMA1 and PCIe slave are connected to the same TeraNet_3_A, while EDMA0 needs to go through TeraNet_2_A and Bridge 2/3 to PCIe slave port.
So you might observe that EDMA0 performs slower than EDMA1 for PCIe transfer, especially if any other concurrent traffic on Bridge 2/3.