Make digests collated by group optional?

I've been busy working with the Message Digest module and related message modules to get a working daily digest for a website using Organic Groups.

From the tests I've done the message_digest_cron function is sending out separate digests per group, which I imagine is useful in some cases, but for the site I'm working on (and I presume this would be the case of a good percentage of other sites needing a digest) then we want each user to only receive a single digest with all the new posts to the various groups they belong to.

So a feature request is to make this an admin option - either digests per group or digest for all groups.

I'm happy to work on this if you think it will get accepted?