I have 3 5.25" drives and zero 2.5" drives. I've been running this case for about 3 weeks. Under normal load (no gaming, web browser, Google Hangout), I've found that the middle drive can run as hot as 55C. The drives on the sides run between 45-49C. My concerns is that when I do run disk-intensive tasks, the drives are going to get and remain above 50C, decreasing the life of the drives.
I'm super surprised that there is no active cooling in the separate compartment, especially as this case is called "high airflow". Typically, you want a fan blowing over your spindle disks at the minimum.
I called support, and they said that no one has complained about drive temperatures. Well, there is one now. I'm considering returning this case.