Spawn or manual setup in Scene view (noobie question)

Hello,

I really need to know whether;

A) I set up all my enemies in the scene view (per level, example level 1 13 enemies, level 2 22) and set up their specific roles manually have them all disabled except the "current level" and once reached level 2 (next level) "enables" the enemies and disables the level 1 enemies or

B) Spawn enemies as they reach the level, for example level 1 used 13 enemies now we move those 13 onto level 2 + create the remainder needed, in this case however things will have to be set up through script, path, etc. as ea enemy has its specific role.

I would prefer to set them all up in the scene view, that way I do not have to worry about scripting too much and taking care of each enemy having their own correct role designated as that will be done in the scene view.

I guess the real question here is, Does this affect my performance? Will I be okay if I have a bunch of "clones" but they are "disabled" up until the level is reached, or is this bad way of doing things, in my head right now it makes perfect sense that its okay :)

I am building a mobile game and will really appreciate professional advice.

Thanks