The J has always resonated with me (more for the neck profile) but sound wise, I think the J can sound like a P but I'm not sure a P can sound like a J!
I listen to 'Fat Time' and Marcus is on the J and boy does she sound hella good both finger and slapping!
I saw that band live. It was amazing. It's a bit of a story, but at the time I was at UMas Amherst and deciding I wanted to study electric bass for real, but they wouldn't let me be in the music department with an electric instrument. So, I went to Berklee and asked the bass department if I could take lessons. They pointed me to Bruce Gertz and he told me to come back a couple of weeks later at 10AM on a Saturday morning. Friday night was an absolute blizzard and it took hours to negotiate the 90 minute drive back to Boston from Amherst. I showed up the next morning, with the streets silent and covered with snow. Bruce answered the door and told me he had a gig with Stern (??? I had no idea) the night before and they still hadn't gone to bed. But then he invited me in and this chubby greasy haired guy came out of a back room and stumbled forward, leaned on my chest and asked me if I had anything to get high on and tumbled into the kitchen. I had no idea who he was. Bruce attempted to give me a lesson, but it took a long time and was kind of half-hearted.
About three weeks late, Miles played at UMass and I look up on stage and, Oh my god, it's that guy! He was transcendent. That summer, I transferred to Berklee and saw Mike and Bill Evans (sax) play around Boston regularly in little clubs. Amazing shows.
Meanwhile, Marcus was starting to produce, work on movie scores, and engage in a busy session life, so I didn't get to see him as much and up close and personal as I did Stern. That was a great time for music in Boston (Bill Frisell every Saturday afternoon for free at a tiny club in Cambridge where he got ignored by the clientele who were drinking getting ready for their Saturday nights!).
On topic: I discovered Fender basses about 18 months ago and I'm loving playing Jazzes. I'd been playing all kinds of other basses for decades, but finally came around. What great sounds!