Hi Vivek ,
In 3.X ,working with Structure only mode was better .
In 4.X it is based on number of variables/formulas used in the report because not like 3.X we have variable dependencies are maintaining locally in Webi Engine .You can observe this by deleting the variable which is being used in some other variable.
Webi Client is better than BI Launchpad ,because there is no network dependency untill you save to enterprise.