I’m well late to this party, but wanted to share that I successfully added an MP500 (J-NP500) stylus to an MP150 body with excellent results, even though it’s not the recommended upgrade for the MP150. The resulting sound was a nice upgrade over the MP150 cart and stylus. In fairness, I haven’t tried the MP200 stylus, so can’t comment on those differences, but the J-NP500 stylus can definitely be added to the MP150/MP200 body.
The MP150H (nude elliptical on a tapered aluminum cantilever) was ~ $311, and had excellent midrange texture, spacious soundstage, and outstanding separation. Mostly very impressive. The treble had excellent air and detail, but slightly more emphasis on sibilance than I was used to with my AT-VM95SH nude shibata. The MP500 (superfine line contact diamond on a boron cantilever) tamed that slight emphasis nicely, and then some, retaining many of the attributes of the MP150 and enhancing others. The addition of the MP500 stylus cost ~ $256, so it wasn’t an inexpensive venture, but it allowed me progress incrementally, and also saved some cash in the long run vs buying the MP500 outright, which often retails in the $700 and $800 range now. I’m sure it’s not exactly the same as an MP500, but the resulting sound is very pleasing IMHO.
My understanding is that the MP100/MP110, MP150/MP200, and MP300/MP500 share the same bodies, and only differ by stylus. It’s worth noting that the MP200 and MP300 allegedly have essentially the same nude elliptical diamond on a boron cantilever, but their coils differ slightly. If that’s true, and the MP200 and MP300 stylus is the same, then it’s logical that the MP500 stylus would work well with the MP200 body also, as well as on the MP150 body. If you have an MP150 or MP200, a J-NP 500 stylus will work just fine.