Its not that hard to set up.
the most work gets in enabling/disabling gates, other then that, its quite easy.
I would recommend doing it yourself, no copy pasting, following the tutorial and struggling through. This way you will learn a lot about inputs/outputs, how the entire system works, etc ...
when you are using a prefab, you will not gain this knowledge. If you've done it once, I have no problems with using prefabs to save time. But you should at least know what you are using.
I have my own personal prefabs for some gametypes, mainly for testing purposes.
Doing it yourself, may take longer, and it is harder. but in the long run, you become a better mapper, and you will have tons more control over entities, and will have a better grasp at whats going on, or whats going wrong when things are not workin as they should.