I have to agree that anyone who uses or plans on using Daz on a regular basis should know that most items will require some tweaking because of the differences in surface settings. I'm specifically referring to textures here, map settings will need to be adjusted lights will differ, or not work if they are poser specific volumetric or ibl/ao..etc. I've posted a number of material settings for various products on various forums here and at Daz. For instance, skin tectures; I almost always add ah-skin shaders to the vendors supplied base, adjust bump settings and whatnot. Same for hair and a lot of cloth items...I rarely leave them as is. But it has been my experience that most basic textures will load ok. If I understand correctly, Ghostofmacbeth has a few textures floating around that work fine in Daz with a minimum of fuss (adjusting bump map values). I've bought stuff from Aery-Soul, Billy-T, Orion1167, and Dm-Marforno among others and they all work fine. Like I've said, bump maps need adjusting, plus displacement (if any), but the products load with no issues.

Real compatibility issues arise when the product uses specific Poser only features, 'optimised for Poser 6/7' is a good warning. The Evolution Eve texture is a good example...all the supplied Texture poses are for Poser6+ but they still load ok in Daz as they make use of texture maps in the material. As I really don't use Poser, I'm not familiar with any poser specific shader node bits I might be missing out on. I still make use of it and it works fine.

I have noticed products though that do seem to have issues. Specifically downloads with wonky directory structures that don't match any specified file paths, or sets that take absolutely forever to render. There is a Tek by Design freebie i deleted because of a wonky directory structure (although I have 2 others from him that load just fine) and the Sparkyworld sets take absolutely forever to render...to the point where I won't use them. I've loaded the same fully geared V4 into scenes with a Sparkyworld set, and with 10 blocks of Dystopia...the Dystopia renders fine, Sparkyworld bogs my system...and i run a better system than most.  His meshes aren't poly heavy for the most part, but on close inspection, it looks like he ran a smoothing function on his pipework to eliminate any flat surfaces. The result is some 20 odd objects with a ton of polygons. His textures are small yet decent looking, and the scene itself loads fast...but a few objects in the mesh make render times atrocious. Not to knock Ol' sparky, but the point is any issues that arise may be surprising. (out of curiosity I'm doing a render now I'll post the results if anyone is curious....4% at 11 minutes so far)

I think a lot of vendor headache regarding Daz support might be solved with a FAQ...as well as some clear links to the Daz manual and tutorials. Most new users I run across have no idea where to look for these things and they tend to be somewhat scattered.

As to what I think about V4.2....umm...well...I'm kind of underwhelmed. They did fix a few issues, one with the poser morph brush, one with the floating unibrow, made ALL morphs injectable (you need to inject to use em), and added a male morph with 3 different heads. There are install issues of various types, all depending on how you're setup. I have problems because of two V4.1's in two separate runtimes on the same drive. this seems to have been fixed by taking the second runtime out of Daz completely and deleting the saved character I had made before doing this. After some test runs, I think I like the old one better. the base V4.2 loads fast, because she has no morph data attached, but any characters saved with injected morphs take a long time to load in my experience...longer than a similar character made with V 4.1. I also think the old version had a better joint system, this one seems to mangle really badly, very quickly, about the hips. I may have more to say as I work with it more. One thing of note...any male character you make, while looking decent...will have no pants! ( and no nads either...Victor's been fixed).