To just read the patches, patchwork may help. But to reply, still
have to go back to the email client.
Probably patchwork can be extended so that one can compose a reply
(i.e. many comments) on the web UI, then get a plain text email in the
end to be copied and pasted into gmail.
From my own point of view, it will probably be nicer if patchwork can
organize email replies in a tree structure so it's easier to follow
the context. That would require each email reply has exactly one
email parent, which is usually the case.