A couple months ago at a homebrew comp I judged a kellerbier pilsner. Had to read through the guidelines, it was the first kellerbier I'd ever had. It is basically supposed to have some diacetyl, and possibly acetaldehyde and DMS, plus be more bitter, a bit hoppier in aroma and flavor, and lower carbed. Turned out to just be a good pilsner, nothing young about it. I was almost disappointed. Don't remember the score I gave, but it probably would have been higher if it was entered as a normal pilsner.
At any rate, I've never had the balls to brew a beer I meant to drink young. I'm pretty patient and never really had the drive to get it drinkable ASAP. With that said, I don't see why a hop heavy session IPA couldn't be served young. The hops will cover up most any young beer off flavors, except maybe diacetyl, which could be avoided using a clean yeast.