We use uddeIM for private messaging of confidential information. It would be extremely helpful to have subject lines; however, when you are in your inbox, you can see the first few words so that helps some.
I could not find the FAQ, but this site confuses me because I don't use CB. I did search. I can see how many users would not use a Subject line, but it depends a lot on the function. If you tested my users, 99% of them would use Subjects. I have 3 foster children and probably more than two dozen team members. Definitely could use more ways to organize messages. So I think it just depends.
Please do not think I am anything but grateful for this app. It does what we need, and I don't think there's anything else like it.
On the subject of features (sorry!), besides subject lines and print buttons, are you thinking of allowing sorts by date, sender, subject... And/or folders? Also options on how many messages to show on the Inbox (on the user's frontend).
And regardless of whether any of these things happen,
THANK YOU, Slabbi!