There will almost certainly be a degradation between what you have in Blender versus what you end up with in SH3D. A lot is done with materials in Blender that is simply not possible to export/import into SH3D.
One of the included woman models in SH3D exported/imported into Blender only has the Base Color texture, and 14K faces. I just d/l'd a reasonable free pose-able woman character from BlenderKit. Her skin has Base Color, Roughness, Normal, and Specular image textures. SH3D (so far as I know) can only handle the Base Color textures natively. She also has 130K faces. She has particle based hair that cannot be exported, so she's bald. I had to manually unpack the Blender textures and move them on disk to get them to import into SH3D with the obj/mtl files. The base mesh was imported all shiny like a T-1000 which had to be removed from all the individual textures. All in all, probably more trouble than it is worth when you look at this comparison. Oh dang! I just realised she has also lost her eyebrows
Notwithstanding the extremely impressive (and very patiently obtained) results of some very talented people, I don't really see SH3D as the tool for realism. Planning, visualising, communicating, iterating, etc. are where SH3D shines. I don't know if the limitation is Sunflow (not developed since about 2007?) or SH3D but, unless you use extreme and lengthy measures like GaudiGalopin3324, your renders will have a distinctive SH3D look. Even Yafaray renders look like SH3D (and this project also looks like it is dying.) Yafaray itself is capable of very realistic renders, so I have to assume that the look is baked into the design of SH3D, and how it drives Sunflow and Yafaray..
As to the original question, I use the furniture library models to gauge scale, space, sloped ceiling comfort, and room flow. I wouldn't leave them in permanently though.
