Hey Dirk, I was thinking about our potato problem and the bulking up VS acne dilemma.
I'm a hardgainer by nature and munching on carbs is essential. Thing is, we've got to balance our plate with more meat to avoid too many insulin spikes. I'd have 2 bowls of grapes and 2 plates (each about 1kg) of potatoes a day and that was just too much for me (funny thing is even with all this food, I wasn't gaining that much weight). Now, I'm not saying insulin spikes aren't essential PWO, they are, but I guess there's a limit to the number of times we should do it. Hence, add more meat to your meals and avoid eating "clean" carbs - balance it with fat&protein.
I find it helpful. Good luck and keep me updated.