Is there a way (script option, exporter option) to export a .psd/.psb file with nested layersets to another layered .psd file with a flat layer structure for greater compatibility? (i.e. CS6/CC/CC '14 to CS4 or older?)

[SPONGEZILLA]

Just looking for a solution short of having to go in and manually delve through hundreds of layers and reorganize the .psd.  There's a lot of vector elements, layer effects and blending modes as well.  It'd be nice to see Adobe include an exporter for older Photoshop versions that can take a newer file and regenerate it making whatever necessary changes to maintain compatibility across older Photoshop versions and even for cross-compatibility.  I know that's not necessarily in their best interests for additional sales, but it is in the end-user's best interests when they collaborate with others across various file and application formats.

[xbytor2]

The first problem here is Layer Styles, if I understand what you are trying to do correctly. You can have arbitrarily nested Layer Sets/Groups (each with its own Layer Style) that contain Layers with their own Layer Styles. This means that for a nested layer, you would have to take it's Layer Style and merge it with the containing Group(s) layer styles in the correct order. Then you have to do the same thing with Layer/Vector Masks and whatever else is involved. It's a non-trivial piece of work. It's not intractable, however.

There is also the problem that some parts of the Layer Styles are binary blobs that make merging at the JS level impossible.

If someone has implemented this, I would love to see the implementation.

What you actually need may be a lot less complicated than the general case. If so, you may be able to find someone to help you out.

I wish you luck.