Fourdee

I think the issue here is an overall frustration by the core team due to many factors: stress, update failures (including ones that happened due to human mistakes), trying to support too many boards and too many features at once, failed expectations of users, board vendors and upstream developers. And this frustration exits randomly in random places, which definitely should not happen in public, especially for a relatively big and popular project.
 
(off-topic) Unfortunately a lot of both kernel and non-kernel issues are out of our control too. And there will be those issues when dealing with cheap and popular low-end devices (like OPi Zero) that have close to zero software support from vendor (well, cheap things are usually cheaper than other similar things for a reason).

Looks nice, is pretty expensive and I don't see the necessity especially given the huge amount of efforts to replace the heatsink (others reported that earlier)
 
I don't know what I'm doing wrong but I repeated the test done by your tester and get rather different numbers (room temp ~23°C, stock heatsink):
 
 
 
38°C idle and 56°C with the light 'stress' workload. What am I'm doing wrong?! Might settings matter?
 
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Welcome to ARMBIAN Ubuntu 16.04.1 LTS 3.14.79-odroidc2 
System load:   0.00            Up time:       6 min
IP:            192.168.83.81 
CPU temp:      39°C           
Usage of /:    32% of 7.0G   
 
 
[ 5 updates to install: apt-get upgrade ]
 
Last login: Wed Oct 12 20:03:41 2016 from 192.168.83.91
tk@odroidc2:~$ stress -c $(nproc --all) -t 600
stress: info: [1525] dispatching hogs: 4 cpu, 0 io, 0 vm, 0 hdd
stress: info: [1525] successful run completed in 600s
tk@odroidc2:~$ uname -a
Linux odroidc2 3.14.79-odroidc2 #8 SMP PREEMPT Tue Sep 13 23:00:48 CEST 2016 aarch64 aarch64 aarch64 GNU/Linux
tk@odroidc2:~$ cat /etc/armbian-release 
# PLEASE DO NOT EDIT THIS FILE
BOARD=odroidc2
BOARD_NAME="Odroid C2"
VERSION=5.16
LINUXFAMILY=odroidc2
BRANCH=default
ARCH=arm64
  BTW: Even running cpuburn-a53 doesn't lead to throttling on ODROID-C2 with default heatsink (temperature after 10 minutes just 75°C and SoC still happily clocking at the highest clockspeed).
 
No thanks, I'm pretty satisfied with the stock heatsink (Hardkernel did a good job here). But here at Armbian we always do the necessary fine-tuning for the boards we support and that might make a difference?