Horizon's excellent performance at checkerboard 4K vs the native 1080p of the base PS4 version is a great achievement. While the Pro hardware has 2.3x the GPU power of the standard model, memory bandwidth hasn't scaled in step - and it's rare that we see a PS4 engine scale so gracefully between 1080p on base hardware and 4K on Pro (checkerboard or otherwise). That Guerrilla has achieved this with no impact to performance is impressive enough, but the team has pushed the envelope here, handing in more visual enhancements over the base version of the game.
http://n4g.com/news/2021535/digital-foundry-horizon-is-a-technical-masterpiece-on-ps4-and-pro