Tim,.. no doubt there are limitations and issues with PV360.... can you show baseline image(s) of what you want to achieve?
It is not about limitations, it is about being flat-out wrong.
Here on the left is a decal I created for the fingerboard, trying to look like streaked ebony. On the right is unfinished mahogany from the standard SW materials, the closest (not very close) I could come to a "stock" material looking like dark wood.
I have done a bit of image processing over 30 years in optics, illumination and algorithm design for machine vision, so I have a pretty good idea of what is easy, what is hard, and what is possible in this realm. I would think it a fairly straightforward function of a smart rendering algorithm to look at the display of a material to be rendered, ask the user "want me to make it look pretty much like that?". Then, if the user says yes, automatically adjust rendering settings to get pretty close to that. Then the existing "proof sheet" function could be used to zero in on just the right look the user wanted. The "proof sheet" function only serves its purpose if the "default" appearance starts out pretty close to what the user wants. I find the proof sheet default image to be so far off, always on the way-too-bright side of things, that none of the current adjustments come even close. In fact, even Powerpoint does a much better job with simple brightness and contrast adjustments.
That's an interesting looking headstock/neck setup there! I love the arc-shaped string tree (at least that's what I think it is).
..yeah,.. the base materials are not enuf if you want more realism,... we all know,... PV360 is basically Modo.. we don't get the full edit capibility of Modo,.. so,.. as is, there are options or ways for creating your own custom *.p2m material file (not a decal).
.. and the wood you are trying to mimmick.. streaked ebony and mohagany... so, you will need to find or take a good pic using raw images and textures (~negatives) which get you closer,.. plus tweaking the settings and environment/lighting..
(attached raw images found on the web.. and a nice link for wood..)
There are several techniques that you can use to compensate for the innaccuracies of the rendering engine and from what you've desribed in your tort, it sounds like you're either using too bright of an HDR environment map or your reflection and environment lighting values are set too high.
I've noticed that Solidworks default interface settings seem designed for making packaging machinery, greenhouses and other medium-sized equipment. As a result, everything from their spinner increment values to environment settings needs to be recallibrated for smaller rendering subjects. I design consumer products and electronics. I've faced this issue a lot.
My suggestion is that you first change your environment map to one of the studio maps, as most of the defaults are intended for outdoor scenes-and then adjust the PhotoView 320 lighting values.
If you're using any solidworks lights during your rendering, you'll need to adjust these values quite a lot. HDR environments usually wash out scene lights.
You can also make adjustments to the rendering iitself in PV including luminosity, input white and black and bloom effects in the rendering window itself:
These settings are based on a some common algorithms used in image processing software and also on a couple of layers that photoview generates for the rendering engine. None of these are as good as having a full-on post processor like Aftereffects.
The last thing, you might consider is that some environments don't render the background as predicatbly transparent. If you open the image in Photoshop, you might find that the foreground of the alpha channel isn't background isn't completely transparent. This has the effect of washing out the image at times.
Finally, PhotoView isn't a full-featured rendering system. The materials and capabilities included with Solidworks are a subset of the capabilities of Modo 901. Since you're trying to render wood grains, and lacquer finishes and probably brushed metal, you need control over subsurface scattering, anisotropy and fresnel and really good control over normal and displacement mapping. For that you should use the full version of Modo.
You might like to look at using Modo materials for PhotoView
You might like to have a look at the post from a few years ago.
Modo Materials can be a bit hit & miss but you might find a material that works for you