CyanogenMod is great but it’s no holy grail. There are some things users should consider when switching. Now I don’t mean bug but proprietary codecs/drivers or year and years unresolved issues.

These are the issues that plague the vast majority of CM roms. Not all devices with stock ROM support all the listed codecs though.

• No aptX or AAC support in Bluetooth
• No support for MIFARE NFC tags
• Shuttering audio over Bluetooth when also using WiFi at the same time (BTCOEX)
• Low mic sensitivity/volume (reports). It may seem ok (because there are plenty of audio streams on a device) but the sensitivity mic just never works as good as on stock ROMs. Most probably it’s related to noise cancellation in Qualcomm Fluence.
• AOSP Wi-Fi Direct is incompatible with some other implementations (Samsung)

Plus one point.

• Having unlocked bootloader means that potential thief could be able to access all phone data (unless you use encryption).