For a long time I had Apple Mail connected to my gmail account without without the "All Mail" folder.
After adding a second account I noticed that mails sent to myself skip the inbox because I had an "All Mail" folder. So now the question rises:
Will I break something by disabling the "All Mail" IMAP folder (within Gmail settings)?
On my iOS devices I noticed that my mail had "Delete", but after an update it had "Archive", and after updating again "Delete". I though the pattern was that odd minor releases delete mail, and even minor releases archive mail... but now I am getting concerned and want to get my settings right.
Now more seriously. I thought that mail clients did not need to know how Gmail deletes mail since any IMAP delete request just deleted mail from one folder, but never from the server. So in theory, I expected to be OK without the "All Mail" folder.