Any recommendations or issues to keep in mind while installing/using a CM5?
It was just a drop in for me, I used the stock thermal pad and the back cover for cooling and it seems to work fine. The audio works. It doesn’t always boot, you have to try 2 or 3 times sometimes and the Reboot feature doesn’t work. Other than that it is very fast and a lot of fun!
Quick question, how does the battery life on the CM5 compare to the CM4? Thinking of doing an upgrade myself but having trouble finding data on this. Thanks!
It goes down faster, especially at a low load. On the other hand, at full power it is less obvious.
With the cm4 I got about 5-6 hours of autonomy, but everything was slower. With the cm5 it’s rather 3-4 hours, but everything is much faster. And warmer 
Personally, I underclock it to maintain good autonomy, less heat and almost as much speed (the SD card becomes limiting afterwards, anyway):
gpu_freq=600 (500 work well too)
arm_freq=1800
I specify that I use it a lot for word processing, light 3D modelling and a little 2D play.
EDIT : And I forget! Good batteries must be used, which can draw 10A in instantaneous power to avoid low-load extinctions.
Thanks for the detailed info! Personally, I’m just tired of the slow browser experience and the laggy YouTube playback so I think a downclocked CM5 sounds like the way to go.
Edit: In addition to the downclock, perhaps undervolting would be helpful too.