I personally think you shouldn't relate to real life seeing blockheads uses completely different proportions and body functions. I think you can refer blockheads to giant teddy bears. They can fill up a whole chair but still not having their feet stick out (I don't have one, but I can see the picture). Although 2x works just as well.
I guess it's just a personal preference then, I really like 2x a lot more and find 3x... well yeah. Besides that, nice furniture, quite basic, but nice regardless.