What i'm really upgrading for is to run Witcher 3 and games like it. Think this is going to cut it?
It'll definitely run it very well. Whether or not on ultra I'm not sure.
Both this PC and the one in your first post offer very similar gaming performance, but this one is $500 less. With the leftover money you could add another 760 (if the motherboard/power supply can support it) and get a massive performance boost for a couple of hundred bucks more.
It won't. It's a MSI H81 mobo and it looks like they started using a 550w Enermax PSU because the Lepa 500w caused a number of RMAs. Overall though it seems like a solid budget build with overall positive ratings on newegg, where it is sold out [again] at the moment.
What games look like on my 4yr old ASUS G73jh - http://www.overclock.net /g/a/36947/asus-g73jh-screenshot-record-of-the-games-as-played-2013-retirement/