Hero 4 Black or Hero 5 Session

I found an extremely good deal on a Hero 4 Black for $20 cheaper than the $300 Hero 5 session. Is this too good to pass? I mean from what I can tell, the Session 5 shoots comparable video quality to the Hero 5 Black and Hero 4 Black. However, the ability to output video via HDMI, shoot 1080p at 120 fps, swap batteries out, have a number of additional features such as slow shutter speed is very appealing especially at the price point being cheaper than the Session 5. The few reasons I love the Session is the small form factor, I'm not one to be seen going around in public with a big GoPro strapped to my head or chest so having a small camera that I could take with me and conceal very easily seems like it could suit me well. Image stabilization sounds nice as well. The inability to swap batteries is disappointing but I feel I could work around this by using a battery pack. So, the Hero 4 Black with superior frame rates and modes at $280, or the small $300 Hero 5 Session?