First: GREAT WORK!
1) I would like to copy email from the "exchange/Inbox" to the "gmail/Inbox" only if the email is not in "gmail/All Mail". Therefor the inventory comparison should be between "exchange/Inbox" and "gmail/All Mail", but the copy should be from "exchange/Inbox" to "gmail/Inbox". This would allow to archive emails in gmail without having them put back into the inbox with the next sync.
2) Delete-if-older-than option would be nice.