OK, here I go again. Personally, while low end is a measurable quantity, I also think that it's the perception of low end that most people are referring to, iow, how loud the low frequncies are. But that's another discussion. Again IMHO, if you're doing 60's and 70's style music, and you can't get enough low end with a J, then I think you're either doing something wrong or you have a distorted view and unrealistic expectations. That said, it's your music and you know what you want, so that's really a moot point. You're just going to have to go with what you like the best. If you really like the way the J plays, you can always put some active pickups in it, if that's your thing.
Another very important thing to remember is that if you're going to audition basses, you have to play them on the same amp to make any comparisons, and preferably on the one you'll be using at home, otherwise you're comparing apples to oranges. The signal chain past the bass is going to have as much or more to do with the sound as the bass itself.
As far as the EB-3 being too distorted, that's kind of the sound that a lot of guys who buy the EB-3 are looking for. The most famous example I can think of for an EB-3 is Jack Bruce of Cream, and that's what some guys are trying to emulate. It doesn't really have anything to do with the sound of the bass itself. It would be like someone watching Jimmy Page and saying that Les Pauls are too distorted.
