I've been printing on the Z3100 from an admittedly marginal computer: I have only 1gig of RAM on an XPPro PC, and print from Qimage. I now use Qimage to interpolate my files. I shoot with a 1DMkII and convert to Prophoto RGB 16bit Tiffs, which are roughly 39mb in size, at 300ppi.
When the printer is set to accept up to 600ppi rendering resolution and make a 24x36 print, and Qimage is set to send the printer a file interpolated at that size, Qimage can finish processing the image but the printer doesn't receive the file. I have worked around this by cutting the bit depth to 8 bits and sending the file under the same conditions, which works. I also have tried keeping the file at 16bit depth but limiting the rendering resolution in Qimage to 300ppi and limiting the printer driver to Best but at 300ppi.
Either way I can get my 24x36 printed, and I'm not sure if I can see a difference in the result. Is there a hypothetical, at least, advantage to choosing one way or the other? Does the Z3100 actually accept and print at 16bit depth, or does it convert down to 8bits?
My hunch is that making the file smaller by cutting the bit depth should actually have less of an impact on the print than cutting the resolution.