i havent but im pretty familiar with apollo. Very high bittering potential but "smooth". For flavor and aroma it can also be pretty pungent. Strong orange citrus with a bit of dank. Not sure how well it would mesh for late additions in a stout, but stouts arent really traditionally based around hops anyway. I would just add a bit at 60min and be done with it. No flavor addition, you are getting the flavors from your malts