Just started using MASH in Maya 2017 this week and it is really cool! While it is marketed as being a Motion Graphics tool, it is ultimately an amazingly powerful object instancer/duplicator. This is my first test with it and basically... I don't think I'll be needing to use EITHER particle instancing OR the SPpaint3D script anymore. Which is awesome. i.e. MASH has geo paint built-in which is ultimately way more powerful than SPpaint, while its instancing tools skip the need for writing particle expressions on custom attributes, caching, runups, etc. Another big plus is that instanced objects on a surface, by default, orient themselves to the surface normals, which is why I used grass for my first test. While this was doable with particle instancing, it required a hefty and slow to calculate expression. Anyhow... going to be a big time saver while making the process much more fun!
I've also been building a library of World Machine assets that are ready to import from a Maya shelf, primarily for when I need Mountains/etc in the background. This image was the result of importing one, adding some Megascan materials (which I also have on a shelf ready to go), importing my water plane (on a shelf as well) and... quick island image!