Hi, Just signed up to MacRumours so this is my first post here. I'm about to buy a 27" iMac which I'll use mainly for photo editing. This will be my first Apple machine as I look to move away from Windows. I was interested in the speed gain from having the fusion drive (FD) option but have also read the pros and cons with this Apple option such as the use of different terminals so that any replacement will have to be done through Apple. The other downside with going for the FD is that any upgrade options chosen means you have to order online. Apparently the iMac is sourced in Holland, sent to Ireland to have the upgrades done and then dispatched to my home in the UK taking 3 to 4 weeks! So I was wondering about using a Thunderbolt external SSD (probably 128Gb, same as FD) to intall my regular programs on such as Photoshop, Topaz and the like and also store the large RAW photo files that I work with. I don't feel confident about installing the whole OS on the SSD but surely the iMac comes with a reasonable sized memory cache so working on my photos should be almost the same as having the fusion drive with lightning read and write speeds? Does this sound plausible? I know the standard iMac will take a whole minute to boot up instead of 20 seconds with the FD but starting up the machine once a day I can sacrifice 40 seconds! By using an external SSD instead of the FD I can go into my local Apple store today and buy a standard iMac without having to wait a month. The FD option costs £200 ($320) in the UK so I can save money buying my SSD from Amazon too. Would be interested in anybody's views on my suggestion. Thanks.