Feature request: clean up attachment handling - please!

I’m using Omnifocus on OSX, iPad and iPhone. I’ve noticed that the cellular data usage attributed to Omnifocus seems a bit high, it’s often the second highest consumer of data after Google Maps.
Following this up I checked the backups file and noticed that each database backup is, or was, before I archived, over 10mb. Looking inside these backups it appears that over 7mb of those backups is composed of two images.

So, firstly: a question. Am I right in assuming that Omnifocus backs up the entire database, including any attachments, every time a device syncs?

And if that’s the case, could you please do something about it? Surely at the very least the sync process should check to see if there’s a local copy of a binary file, and not transfer it if that’s the case, and ideally shouldn’t the sync process be using something like Rsync which would only generate diff files rather than multiple complete copies of the whole database.