I just don't think geometry is a big problem when rendering in Blender. There are very few mesh errors that will affect the render in modern versions of Blender. More important are knowing the shader and lighting systems of the software. That's where 99% of render problems begin and end. Not with the models. Yeah, if the models are extremely outdated like Lux mentioned in archive 3d, then I can see where you might have some problems. But most of those problems will also come from the way the thing is textured and uv mapped.

Blender isn't the only software that handles ngons flawlessly now. I think just about all software do it. 3dmax, Maya, C4d all seem to handle them great. The only time ngons are a issue these days is when you subdivide for sculpting or whatever. Zbrush doesn't like them, but that's for good reason. Otherwise, there isn't a software today that doesn't handle ngons with great results. There's no reason to avoid them anymore, unless you intend to subdivide the models for sculpting or whatever reason.