I know this has been asked many times and I have read through many of the posts. I'm looking to upgrade my system that will primarily be used for Lightroom and photography. I'm currently using a rMBP (2.7Ghz i7/16GB/512SSD) with a Thunderbolt LED display. My 100K image catalog is 196GB that I store on the SSD and the Photo images are 1.5TB stored on a Thunderbolt 3TB WD RAID (2-drive). I backup both to a 10TB NAS plus use Time Machine for the system BU. I have had many sleep/wake problems that I believe is related to the Thunderbolt chain, so I'm considering moving away from that when going to the new iMac. Do you think it is best to go with a 3TB Fusion drive and put both my Catalog and the Image files on it? Or, go with a similar setup to what I have now, with a 512SSD to store the Catalog while keeping the Images on the Thunderbolt Drive? As far as performance for using LR, which storage option is going to be optimal? I would buy the 4Ghz i7/395X/32GB + ?? Hopefully someone else has already done a similar setup and can offer advice. Thanks. P.S. If I do use the Fusion drive to store everything, then I would probably use the old Thunderbolt drive as an additional backup drive.