I want to thank you all for the great answers.
Now I have an inkling about fat biking and how much fun it must be.
Right now the bike I want and the bike I need are radically different.
But you never know there may be a fatty in my future.

If fat bikes run low pressure tires then losing a pound or two must make a difference.
Do you have to check your pressure/pump up the tire more often than a road bike?

Nope. Due to the volume of the tire 1 psi is a heck of a lot more pump strokes than it is on a road bike so it takes a long time to lose enough air for it to make a difference. I haven't check my tire pressure since late November aside from the daily squeeze test.

It loses much less because of less pressure.
Most change I see is when it gets colder. I basically check pressure when my front tire starts to self-steer.

I have to remind myself to increase the tire pressure. I had it at 4psi but lately it seems like a real struggle going just 4km.

I don't remember having that much difficulty even when I used to bike commute. Maybe it's my age.

That makes perfect sense.

At 4 psi, it would be a struggle for most

That's my starting PSI for soft snow. Some go much lower. 0 psi is not unheard of.

I rarely check my pressure. I tend to just squeeze the tire. Squashy beachballish (about 5-8psi) for snow and basketballish (about 15) for trails.

I don't check pressure for same-same conditions, but I often go from riding frozen lakes with low pressures (5-6 psi) to riding roads the next day with high press (8-12 psi). So I end up checking and adjusting for the conditions.

Depends on the particular road bike, but yes, but because of the aforementioned temperature changes affecting it far more.

I can't really tell the difference between 60 and 85 on my Paselas. I can easily tell a difference between 6 and 8.5 on the fat tires.