I have a 15-in, Mid 2009 MBP with a WD 750GB 7200rpm drive and have recently added a SSD set up as a fusion drive. If I remember correctly, I took a decent hit on battery life and warmed things up a bit with the addition of the 7200RPM drive, so now I'm wondering what impact moving to a WB 1TB 5400RPM drive might have? I know that's a lot of variables, but maybe somebody here will have some experience before I invest the time and money in an experiment that may not pay off. My mac serves two purposes. I run Adobe Lightroom and Photoshop with a local catalog and my raw images on an external drive. The machine get's crazy hot with photoshop pushing the CPU and graphics card, so heat is an issue. Lightroom doesn't seem to hit the HDD unless I happen to browse some images I haven't touched in a long time. I also do a fair amount of programming. This activity does not load the system or hit the HDD, but I would like to be able to go unplugged a bit longer. My guess is that the HDD is filled with music, movies and docs I don't touch much. Would I gain back much battery life or lose much heat going with a slower drive in the Fusion setup or is the gain small enough to not be worth the effort? For those interested, this is the mid-2009 with the wimpy SATA controller that refused to play nice with some SSDs. Intel 520 was running at 1.5 Gigabit, but a Samsung 840 Pro seems to be working just fine at 3.0 Gigabit. HDD is a WDC WD7500BPKT-60PK4T0 and it has always worked but seemed a little power hungry when compared to the stock drive. SSD is in the original drive location and HDD is a MCE adapter. MacRumors was a great resource when sorting out the SSD challenge, so I thought worth posting a working configuration with the hope that it would help somebody else.