The Surge S2 will be Xiaomi's second attempt at creating an in-house SoC. Details of the chipset have leaked and it looks rather interesting, with performance values that we expect to trade blows with the Snapdragon 821.
https://www.notebookcheck.net/Here-s-all-you-need-to-know-about-Xiaomi-s-upcoming-Surge-S2-SoC.279754.0.html
While the Kirin 960/970 offers competitive CPU/GPU performance to the Snapdragon 835, it does so at nearly twice the power useage, and ran very hot. Typical of their lineup even through the midrange compared to Snapdragon SoCs and it should be stated everytime the performance of the platforms is compared. Qualcomm is well ahead of their competitors when it comes to power/heat budgets. Hopefully Xiaomi doesn't make the same mistake