We can have a first clue about the performance as Rockchip RK3399 boxes and one tablet are now showing up on GeekBench.
Recommended Models, No Regret to Buy:
MECOOL KIII PRO Hybrid DVB TV Box, 2018 Best Featured Model
Mecool M8S PRO L, 2018 Best-selling Model in EU
MECOOL M8S Pro+ TV Box, (Best Seller of Quad-core TV Box)