I have been using a Sinarback 54H on the Sinar-M for the last 2 months in 1 and 4 shot mode with success. 22 mpx. is more than enough for me and 4 shot is perfect for copying artwork. No problems with the hardware. I am getting used to CS 5.5.1. and patiently wait for the eXposure.
I tried to shoot 16 shots several times and always had some artefacts on the borders of the objects and in the areas of transition of colour in the 100% view in PS. The 50% image looks better. Downsizing helps, I do not output for the prints more than A3. Having the problem I tended to ignore it for a while being satisfied with my 4 shot images. Now I was asked to shoot Russian post stamps and I would like to use the 16 shot mode of the back.
I would like to understand whether I have a hardware problem with my back. I have very limited experience with pixel peeping and for me the images look funny.
What is the output size of the image you are shooting? Unless the output size is extremely large I would continue to use the 4 - shot mode.
16 shot actually overlaps pixels and serves to increase file size for extremely large prints. Many times it can appear softer on a small image. I have also seen 16 shot out resolve many lenses and I know with the P3 set up you really need to use HR lenses either in CMV or CAB mounts. I personally have never tried them with the zeiss lenses on the M camera by itself in 16 shot so I can't comment on their ability.
Personally I would continue to use 4 shot and use the 120 macro lens.
Dodd Camera - Chicago