is it worth it to upgrade from r9 270x to r9 280x?

Solution
Nope, the 270x is a perfectly decent card for 1080p and you're not going to 'feel' the difference imo

Turning up the AA settings is just bragging rights anyway


in indonesia the gtx 970 and r9 280x have almost $100 difference in term of price (gtx 970 more expensive than r9 280x) i can afford r9 280x but not GTX970😀
 
Short answer...NO... You probably won't see any difference at all... If your motherboard supports it, you could Crossfire with another 270X. Are you experiencing lag or come across games you are unable to play... or did you just want a fast card?

Back when I was using an Nvidia 8800GTS-512 I decided to upgrade it a bit and bought the HD 6850. I was so excited to get that new card.. but was disappointed a bit because I honestly didn't notice that much of a difference between those two cards. However, when I Crossfired the 6850's... I noticed a nice little jump... and it served me well for a few years... then I recently just bought the 280X from Newegg a couple of weeks ago. The performance is a tiny bit better with that single single card when compared the the 6850's in crossfire... but the area that made the biggest difference was the added VRam in the 280X: 3GB as opposed to just 1GB. I noticed much smoother gameplay. I have yet to push this card to the limit...