Sadly its pretty much any data set type...
Workspace is great for like top 25 examples of a reporting breakout... as soon as you hit it with large numbers you see what its like...
I like to use it to visualize segmentation reporting I need then apply the logic to a data warehouse query...
A typical workflow for me:
In 30 mins i can run through dozens of reporting options, refine til I get a set I like.
Then I build final pull in data warehouse..
I now get usable data files in my case for millions of lines of data...