Thanks for replying, as I shoot Raw I will stick to NX@.
Well, all recent Nikon cameras embed a full size jpeg preview inside the nef file, which is what Photomechanic sees. This jpeg preview is rendered by the camera according to the settings the camera is set at (sharpness,contrast,colour profile et cetera), which also translate into default settings of NX. So indeed, you can use PM to see your photos at 100% zoom with basically same view as in NX.
As you are looking at the photo at 100% magnification, you can easily see if it is critically sharp or not inside PM.