I've removed a lot of bloatwares and seems like my phone is smoother.Not always but it may blow up in your face. I've gotten away with it before... depends what was blocked. If it crashes I just factory reset* and move on. Incentive not to repeat mistakes.
Generally firmware updates are a mistake if the system is running well; you have little to gain and a lot to lose.
* my critical data is always redundantly backed up because anything can and eventually will happen when it come to data.
ONE UI 5 is coming soon and I wonder about updating my phone, so thanks for your explanation.