Yes I've joined several. You can set it for 1 daily email for all your groups but even that won't show all the posts. Yahoo has made it so some files can't be downloaded in some groups so this is helping. It's very private too.
If you post on a Yahoo people can google your name and your post pops up along with other info. That doesn't happen with Sgrouples.
I think my biggest problem is that I do not see all the notices in the daily digest so I might miss something. The notice shows some things and then it says, "To see more go to the group."