What kind of tasks?

I am not necessarily disagreeing with you but context is important. I've had 918+ and 923+ and the cpu has idled through all my years of NAS-oriented usage.

Originally I planned to also run light containers and servers on it, and for that I can see how one could run out of juice quickly. For that reason I changed my plan and offloaded compute to something better suited. But for NAS usage itself they seem plenty capable and stable (caveat - some people need source-transcoding of video and then some unfortunately tricky research is required as a more expensive / newer unit isn't automatically better if it doesn't have hardware capability).