FS7500/FS7600

Anyone using either of these? We are interested but the information on the website is lacking. Is there storage in these or are they a front end to a PS series? How are they on speed/performance? We have about 1500 users and close to 6TB in user files. Plus, we need storage for another project starting at 2TB and growing to 10TB. I was hoping we could provide some storage tiering based on file usage as well.

Thanks

Troy