Depends on your weight I guess. At least for me being sub 70kg, the RXL bars have been fine. I do a lot of out saddle sprints and climbs with no problems. As long as you torque your stem bolts properly, they should hold up fine. I'm running a -17° degree stem, so I prefer the separate bar+stem combo.
Unlike some people, most my AliEx purchases have been very good. There hasn't been many issues with the equipment I've used.