Thanks for the input and info everyone! I would love to get this bass for $800 - not sure if he would let it go for that (I doubt it!) and not sure if I'm going to make a bid, but it's been fun to learn about these basses, especially from those of you with direct experience.
I also play my 8-strings with pick - I've messed around a tiny bit with fingers, but it doesn't really fit for me. Slapping actually works a bit - I do an up-and-down technique with my thumb in the same direction as a pick, but don't use that technique much at all anymore.
I have a few recordings I've done with various 8-strings I've owned, thought I would post them for fun:
This track features my first 8-string, a Tune - two tracks of it in the intro, then Mustang reissue in the middle, then the Tune again at the end, both times through my RE-201 Space Echo:
Then I got a Rickenbacker 4003S/8 and recorded a song I originally came up with on the Tune, slathered in even more delay:
8 Echo Dr. (experimenting with SoundCloud with this link)
I also got a Rickenbacker 4008 - their earlier 8-string - and recorded this which has both distorted and clean tracks together, though the distorted track is more obvious:
Finally, my most recent recording with the 4003S/8, this time with both distortion and octaver! Total overkill!
(Greg DeGuglielmo is drums on all tracks and co-composer on "Next to Last" and "Black Walrus." DJ TAKA is scratching the Yes on "Black Walrus.")
The Tune and the 4008 have been sold and the 4003S/8 lives back in Boston, so I'm always kind of on the lookout for an 8 for here in Oakland!