About GMail archiving: Really not? (I haven't read trough this massive review yet.)
At least on iOS it is possible to convince the delete button to archive. (By setting the trash folder to 'All mail', if I remember correctly.) I would imagine that Apple Mail should be at least as configurable as its iOS counterpart.
iOS supports archiving perfectly fine. No need for any tricks.
Lion kinda does. You can archive but doing that will actually create an “Archive” folder and moves the mail there. That’s not the expected behavior when using Gmail. (The expected behavior would be to move the mail to the “All Messages” folder, or, in Gmail lingo, to remove all labels from the message. iOS does that, Lion doesn’t.)
Archiving is handled through IMAP delete by default. Check your GMail settings and go to the "Forwarding and POP/IMAP" tab. Most likely your setting for "When I mark a message in IMAP as deleted" is "Archive the message (default)."
That was the point of gmail... five years ago. And then they added delete, because there are some message which never again need to see the light of day.
At least on iOS it is possible to convince the delete button to archive. (By setting the trash folder to 'All mail', if I remember correctly.) I would imagine that Apple Mail should be at least as configurable as its iOS counterpart.