Ugg, ontap edge.. anyways...
I don't know how you lost that battle b/c vfiler-dr is worth more to a business DR strategy than the reduced cost of ontap edge. This is just my opinion, There's a difference between price and cost, and your management is making the wrong decision.
As for managing different name spaces, it's hard to manage different name spaces, how are you going to correlate what filer is joined as what.
Please take this as constructive criticism.