Web Acceleration vs Ram Cache

I just got an answer from one of my company's F5 instructors: In fact, it's very simple. LTM Ram Cache = uses the unallocated RAM space on your BIG-IP. Each time you add the Web Acceleration profile, it takes the RAM you assigned from the unallocated space of RAM. So at some point, you can run out. It doesn't regroup it and doesn't use your disk. WA aka Web Acceleration aka AAM uses ONLY it's reserved RAM portion that you reserve when you provision it. When there isn't enough RAM it sends it down to the disk space that it reserves when you provisioned that module. So all in all, if you want to do a very simple RAM Cache on the BIG-IP for one or a few Virtual Servers, then LTM RAM Cache is enough. If you want to have real Caching on the BIG-IP that uses both RAM and Disk and can serve a bunch of Virtual Servers, then purchase AAM.