to start with I would get rid of the auto negotiation. Fix the speed and duplex setting on at least one side, preferably both. In my experience, auto-negotiation is problematic at best, especially between different vendors equipment.
I am quite interested in an answer as well. The big problem I see is the cost of a 7200 with a DPT card. What are the bandwidth requirements at each of the drops? It will be interesting to see if there is an affordable ring technology for "small" ...