Here is something else to confuse you or help you

Bicycle Rolling Resistance | Rolling Resistance Tests

Many factors affect rolling resistance, quality has a lot to do with it and yes I am in the camp of the thinner the faster with some exceptions though some will disagree.
Knobby tires on the road will slow you down and yes the wider the more comfy. So a lot depends on the type of riding you do.
I personally use a road bike for street riding using 23 or 25cm wide tires, while they are excellent for some fast cruising on nicely paved roads, there are plenty of beat up secondary roads here in NJ and the thinner tires will beat you up and definitely slow down your ride over those bumpy roads.
So it's all about finding a happy medium for your type of riding.