I took a look at this comparison chart and was blown away! The biggest performance boost is on the iMac 5k, and I think that's on the standard entry level GPU. On the 295x it might be even better. Downloading right now and will report back. I didn't like Photos app so much, mainly due to endless bugs, but I LOVED the speed. It made Lightroom feel like a turtle. Hopefully now they'll be on par with each other.