I'd like to ask what motivated you into buying mobi in the first place?
You asked; Are they worth keeping? I don't see how anyone can answer that question without knowing what they are, As devalued as Mobi is overall, many domains still hold value to some resellers who haven't quite given up on the TLD yet, mainly because their ego wont let them.
Franky, I would do everything I can to liquidate them from your portfolio.. Would you rather devote your time to selling dot com's to end users for 10K +? OR selling mobis for $10 a pop to resellers?