16 bit Plug Question

The iPF 5000 is a 16 bit device so it is only speculation but the only way to send it 16 bits is the plugin until a 16 bit RIP is available or windows vista (should support 16 bit print drivers) So my guess is the difference that I see is from feeding the iPF5000 the 12 bits the 5D recorded? When I am home I'll test the theory with the same image in both 16 bit and 8 bit mode (through the plugin). I also find some images look better with some noise or less resolution but that is another issue. My tests of the iPF 5000 have been, high resolution, sharp, color images on glossy photo paper. I'm hoping the upcoming LL review will shed some light on this.
Marc