My oldest son rode with on my motorcycle for the first time yesterday. In fact, he is my first passenger ever.
We just went a few miles to meet some folks at a restaurant. He's close to 60 pounds so it wasn't a big difference, but I did notice that I used about 1000 more rpm before shifting than I normally do by myself. I got just enough for the v-tec to kick in at 7K and I think he liked the way it "growled" more when it went into 4-valve per cylinder mode.
His comments were, "Your bike is noisier than Mommy's", "Your luggage rattles over bumps", and after crossing a bumpy railroad track, "your seat is harder going over bumps." No complaints though. I think he could see just a bit better than on the ST because the pillion is higher relative to the rider on the VFR than the ST