Hi Probably not that much use as a response but...
A few years back the company I was working for tried to set this up and, in spite of having separate specs etc, we did encounter some problems.
Specifically, myself and the other developer found that the ER would completely disappear from UBEs that were working on. You would be in RDA, save your changes and come out of it then, when you went back in all the ER had gone (not just the latest additions but every single line). This, as you might imagine, was a little frustrating.
I suspected that this only happened when both developers tried to use RDA at the same time but, to be honest, I put more energy into shouting to get a fat client each than I did investigating the problem.
Ste