I have a '98 55-94 that came with the Bartolini setup. Trying to get a little brighter sound, I replaced the preamp with a John East Unipre 5 but left the Bart pickups installed. It was a little more flexible tonally but really still kept the warm smooth Bartolini character. I think most of the character comes from those pickups.
I have since reinstalled the stock preamp...another Bart equipped 5594 reminded me how great of a sound it is. I'll install the Unipre in something else when inspiration hits.
Edit: Added a picture....everybody loves pictures!
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