Yes you can write stuff back to disk, so real amiga can read it.
However, not sure about Copy protected disks. Doubt something like X-Copy would work for those.
DOS based disks, like workbench, etc etc. will work fine.
Every Standard ADF (880KB) works fine, even NDos Disks since they don't have any copy protection info on them

If you want to do that, just connect the Greaseweazle to a PC and you can write back anything that has been preserved, including copy protected disks ... but that is not possible on the A600GS itself !