Are there any advantages to using a live connection if your customer is not really expecting real time data. If customer is happy with 1 day old data.
What other benefits can be gained from using a live connection?
What kind of testing is recommended to gain a better understanding of which is best?
Depends on how slow your database is. I usually start with a live connection and only when you want extra performance or want to take the load off the database that you then create an extract.
On small Excel files, an extract is not needed, but as the file gets larger an extract makes it faster as well.