If you only need to test that the operation has succeeded, you can also use the OpcLabs.BaseLib.OperationModel.OperationResult.Succeeded property.
This property is not serialized into XML. Instead, OpcLabs.BaseLib.OperationModel.OperationResult.ErrorMessage is serialized. Deserializing from XML creates a base OpcLabs.BaseLib.OperationModel.OperationResult.Exception object with just the message.