Actually, rendering at a larger size and reducing just adds a bit of blur to an image. It's not extremely noticeable in a side-by-side comparison, but hair and other details will be softened. Shrinking an image eliminates pixels of detail and requires the software, doing the reducing, to decide which pixels to toss. It's usually worthwhile to take any Poser image and bring it into Photoshop, or other image software, to enhance colors and contrast.