Can someone please explain why I get so much better signal strength with my C2 over my X’s, despite the same SIM card and exactly the same location?
I used the Cellmon app to illustrate differences and the only thing I can see is that my X10III is using a different band, if that even matters.
Band definitely matters. But if it is pegged at 100%, that looks buggy.
Yes, that’s what I was thinking to, but everything is working perfect.
Using your BBK app it also looks like C2 is way better.
I have only ever seen 100% signal strength (for LTE) on my C2. It is that good! 
As living in rural area, I have never ever seen 100% signal strength before, so I guess I really did hit a bug.