12% of my home smoked malt would give you a noticeable smoke taste, but barely in a porter. 12% imported rauchmalt probably won't be detectable depending on it's freshness. It really all depends on whose malt you're using, how fresh it is, and just how much smoke flavor you want. I use that yeast for stouts and porters all the time, smoke won't clash with it, and smoked porter is an excellent beer when done right.