Sorry you're in the position of needing to sell the 968...do hope it works out for you.
My opinion (worth maybe almost as much as you paid for it) is that you can ask & should get more for both options. Maybe $3,000 more.
However, I really don't think an LSD changes much performance-wise for a street car. This is based on last year completely rebuilding a 901 transmission for a 914 and adding an LSD, billet intermediate plate, all new synchros, sliders, dog teeth, etc. It's great for "bragging" rights, but not so much difference in the seat of your pants.
Maybe we need to swap in that LS motor with tons more HPs to see a real difference? Yeah, that's gotta be it...so it's now on the list.