First of all, something that was introduced (or it's power has been raised?) in the latest build(s) - the "camera light" when you are on the preview scene. On the same lighting and imager settings that light burns out the preview scene, forcing you to re-set exposure every time you jump back & forth between your actual scene and the preview one. Compare this same material on the same lighting & imager settings. The top is the actual object.
The preview scene is burned out because of that light. Tunning down the exposure doesn't really help, because you can choose between an over bright light spot on the mat. or a dark surrounding. This "preview light" is bad IMO, and we should at least have the option to disable it or control it's power.
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Now to the point:
Why is the material ball a bad preview for your material / texture workflow
1.) It's way smaller compared to the majority of objects on your scene. That means if you fine-tune your texture scale (or noise parameters) on the ball it will almost 100% look wrong on the actual mesh. This problem can be observed in the LiveDB, where people have created materials that look good on the ball, but whose scale is totally off on actual objects (that's why including a way to scale the material is so important). Even if you scale the ball up that doesn't really solve anything, because a ball of a fixed size will always be much smaller or much bigger than some group of actual objects.
2.) Because it's so small you must zoom in like a madman to get a close view.
3.) Because it's a ball It has spherically distorted UV coordinates. This means that important regions on your textures (like text or something) are sometimes not visible at all - because they are lost in the polar region of the sphere. A sphere is good only for noises and is a bad preview for non-generic non-tiled textures that are exactly mapped.
4.) Because of UV distortion and structure of the model, there is little useful preview space, which is mostly located around the "equator" and on the back (because of logo).
5.) A material ball is really not meant to work on when creating materials, but it's more like a (bad) generalized preview, thus it does not fit the Octane material node work flow or the Octane general WYSIWYG type of work.
Ideal solution
Allow the possibility to view the textures on the actual mesh, so that we can move our material creating work flow entirely on the actual objects. For material parameters this is possible to do, but it would be practical to have this ability also on the texture level - when you would click on a texture node the texture would show up on the mesh. (currently it would be possible to hack this behavior with a "dummy" mat. to which you would assign the texture to the diffuse channel, and the assign the mat. to the object, but this is sooooo clumsy that it's not worth it...)
