Personally, I'm just fine with a pretty weak, underpowered phone. I "just" want all of the hardware features to work reliably...
...with the exception that I want photos with decent autofocus, which seems to put me in a whole other category of users.
From the first perspective, the 6T seems likely better, from the second, the FP5. I'm still undecided, but leaning to the FP5 as time won't fix the 6T hardware but will likely improve the supported features on the FP5.