Hi, I finally got the new iMac with the 768GB flash storage (SSD). I'm a first time Lightroom user. From everything I've read, it sounds like I should install LR on the internal SSD, and maintain the catalog, previews on the internal SSD as well. Given that 768 SSD Flash Storage won't be a long term storage solution (size issues) for my photo files, I think my plan would be to put the actual picture files on an external drive. Is that the best approach for me? If so, which thunderbolt / USB 3 would you recommend for this purpose? Would I lose any speed by going external for the actual photo files instead of going all internal? Any advice would be much appreciated, thanks!