Hi, I know this is discussed, but it still seems evenly split. And my brain hurts from trying to come to a conclusion after reading so many threads. I thought maybe if I give I give my specifics, it might be more clear whether or not I should "upgrade" to Yosemite. I'm not a power user, so it's not like my comp is loaded to the gills with different software. But it is an older 2.66 GHz Core 2 Duo with 4 Gig RAM iMac. Apple claims it can run Yosemite. I currently have Mountain Lion on it, and it runs OK, though opening up apps is a little sluggish, ESPECIALLY Safari. Ironically Firefox runs a little better, though I prefer Safari. Have not tested Chrome extensively. My iPhoto library is around 18 gig, if that's relevant. I've seen some complaints about Yosemite being sluggish, so if I see the same level of sluggishness, I can deal until I finally get a new comp. Thoughts? Thanks.