Here are MY views on this topic...how a pickup is actually designed and wound might be more important than placement to define how it sounds.
I voted 2 pups in J-fashion....though I only have one actual Jazz bass. The others are an L2500 (close...kinda), a Jazz with MM bridge pickup, and a crazy Dean with 2 MM pickups close to the bridge (where the inner coils of both pickups are in the "Sweet Spot", and sounds more like a Thumb when using these coils). I chose 2 pickups because I like variety...
A superb custom pickup manufacturer, Howard Ulyate, made a MM-style pickup with one MM coil and one Jazz coil in the same housing. When he uses the MM coil (closer to neck), it sounds sort of like a P-bass. When I used to have a Stingray, I split the coils up like that and my stock pickup neck coil didn't sound anything like his. He told me it's all in the windings...
I voted 2 pups in J-fashion....though I only have one actual Jazz bass. The others are an L2500 (close...kinda), a Jazz with MM bridge pickup, and a crazy Dean with 2 MM pickups close to the bridge (where the inner coils of both pickups are in the "Sweet Spot", and sounds more like a Thumb when using these coils). I chose 2 pickups because I like variety...
A superb custom pickup manufacturer, Howard Ulyate, made a MM-style pickup with one MM coil and one Jazz coil in the same housing. When he uses the MM coil (closer to neck), it sounds sort of like a P-bass. When I used to have a Stingray, I split the coils up like that and my stock pickup neck coil didn't sound anything like his. He told me it's all in the windings...