My final answer is that elFinder was the file manager that ended up being the easiest to implement and it works nicely. Filedepot was promising, but by design, only a filedepot administrator can create a top level folder in Organic Groups mode. This means that if you have your site set up so users can create groups, it will fail creating the folder for the group unless you make all users fildepot admins. There may be a way to change this functionality in the code, but I didn't investigate it I also ran into trouble showing filedepot in a view and/or panel. So, I couldn't get a filedepot display to show up for each organic group.
If you use panels, elFinder shows up as "File Manager" under Miscellaneous when adding content to a panel. So, it was really easy to display an elFinder manager in each organic group. I did have to modify a few lines of code to grab the id of the current group, so that a correctly named directory was created the first time anyone opens elFinder in the group without a directory already being there.