Tires for a stumpy clyde

[chupacabra]

I've read, here and other places, speculation about how tire pressure and size affects rolling resistance. The thought is something like:

The lower the tire pressure or larger the tire the less rolling resistance there is due to the fact that there will be less horizontal movement of the bike/rider over bumps and thus less wasted energy? Also there will be a bigger footprint which keeps the wheel from digging in?

I'm not sure I got all of the right and I'm not sure I believe it all.

According to the above logic, there shouldn't be any 1.9 or 2.0 xc tires. Is there a huge misconception about tire size and rolling resistance. Or is the above thinking flawed?

Right now I am running 2.35 Holy Rollers upfront and 2.2 Bontrager ACX on the back. But, using the same logic I should switch to bigger, especially since it would help with traction on the way down. I am willing to experiment.

Any thoughts on the thinking or tire choices?