I have noticed, their is a slight smoothening effect in Mavericks/Lightroom 5 vs. Lightroom 5 in Windows 8.1 and the Preview of the Systems. In Windows it seem to be, that I can see the noise of the same picture better/sharper than in Mavericks. Systems on an iMac 12,2; Mav 10.9.3, all updates and Win 8.1, all updates too. Do you noticed such a effect too? Is the general calibration of OS X that much of a difference to Windows?