I tried it. Set my swap file, which has a partition of its own, to 512. Rebooted, fired up Poser 6, and tried to render a simple scene at the "finished" setting. (One M3, with conforming clothing and two props.) The same thing happened as before. An "out of memory" warning, then complaints that it can't find textures.

The only difference was the out of memory error message came much sooner. In a way, this was beneficial. It only nuked one texture (the figure's head texture). With a 4096 swap, it nukes a whole bunch of textures. Eyelashes, eyebrows, clothing, etc.

Other than that, it doesn't seem to make any difference.