Hi Tony,
I am not having any idea about ERMS , but i do have a very nice experience with workflow priorities. Workflow have a mechanism for having unified priority across all the nodes and if you change the overall workflow priority to a certain level like 7 , it will become the same for all nodes and the problem is , you cannot change it. To change any node's priority , you need to implment a workitem-exit and change the workitem priority there. This is the way around.
Sorry but i dont have idea about ERMS , if you can be more specific , may be i can guide you.
Thanks
Rakesh