I bought the 5k iMac about 2 and a half weeks ago. I’ve had almost no problems at all. I got the i7 4 GHZ with 295 graphics card and 1TB fusion drive. I bought 16 more gigs of ram so I have 24 total now. Planning on upgrading to 32 eventually when I have the funds. Premiere runs great though with my current setup. I’ve had one Premiere crash in 2 and a half weeks of pretty heavy use. Only really good/bad side is that 1080p files look fantastic in their windows while editing because they’re playing virtually pixel for pixel. However, when full-screening anything 1080p it looks a little blurry because of the upscaling it’s doing. This can be solved with a nice client monitor though.