Yup. I came from Nougat to unofficial 18.1, then when official 18.1 released, I clean installed 18.1
1. I'm using official kernel now. I tried Gamma before, and it was worse! it would heat up, freeze and etc... I don't know the reason, but I think when signal is low and phone switches between 4g and 3g it crashes. not sure though. I read in the forum that installing the modem may fix this issue, but I have no idea where I can find the files nor how to install it!
2. GPS takes almost 10 minutes or more (some times forever!) to get my exact location.
3. How is camera fine? sometimes it takes plain green pictures, sometimes it fails to take a picture, video is frame by frame!
4. I heard that IR works on some Gamma kernels, but haven't tried myself.
5. can't share my screen to my Samsung TV, something that I was able to do on stock rom.
6.

I really don'y know what is going on, I tried to contact the app developers but haven't had any luck yet.
7. My bad, I don't have clipboard "history" (I forgot to mention history. sorry). very useful function, available on stock rom.
8. again another miss from stock rom.
but thank you for responding to me. I have this device as my daily driver and re-installing all apps and redoing settings and logins is so frustrating that I just can't go through with it for a factory reset or another clean install.
I had another issue on my friends device. I installed TWRP and did all the wipes and formats available, (data, cache, etc).
but after installing the rom and first boot, the phone asked for a password! and entering his old password worked!
How is that possible? shouldn't a clean install make a clean slate? like new device?
maybe there are residuals from old roms that create these issues. not sure how his device is working though.