Hi,
Though,I have never worked with cubes but have tried the following steps in Report Studio to know the server name of the reports.This procedure requires selecting the appropriate DSN of your report.Please find the steps below:
Go to the Query Explorer in the report Studio
Click on Queries
Drag a SQL component from the left hand side pane
In the properties pane of the SQL component appearing at the left hand side ,select the datasource appropriate to your report
Type the following SQL within the component:
Select @@servername as server
Click on Validate and then OK
Then view the tabular data of the Query.
You can then come to know the server name that your reports are pointing to.
In this way,you can come to know the number of reports that are using the same DSN as that of the cube...
The number of reports using the same DSN as that of the cube one.. will be the number of reports impacted.
Then you can plan your estimates accordingly required for the changes
Hope this works for you

Thanks and regards
Prerna
pchaudhary@infocepts.com