Should the use of IRegistry in the IData{Provider,Manager}Svc be replaced with concrete RegistryEntry?

There is one and only implementation of the IRegistry interface, and that is RegistryEntry. So is there any reason not to declare RegistryEntry as such, and drop IRegistry all together. This would remove a lot of dynamics_cast in the implementations of IData{Provider,Manager}Svc....

(this is the same argument as has been made for IAlgorithm and Algorithm)