Generally speaking, the concentrations vary wildly from nearly non existant to somewhere apoaching extremely good strength. Joop Homme aftershave balm was the clear winner. Drakkar Noir was the weakest from memory.
But the concentration in any balm or splash has to be less than that in the EDT, or you will most likely have a very red, raw, stinging face.
I wear them together. Basically because unless you buy some weird combination like 200ml of aftershave balm with a 50ml EDT bottle, I'd generally finish the balm before I had finished the EDT. Then I'd have to make up my own balm in the manner I described in the article.