"Loss of a possible mile or so per hour?"

I don't buy it unless your at the top of a road bikes performance envelope.

My 36 pound, now 41 with added riding gear Tour Easy recumbent had a 700 x 28c on it, the tire needed 95-100 psi to protect the rim.
Max psi was 115,,really ? I don't think so... I'm not racing.
The ride was terrible, It beat me to death, every tiny road imperfection went right into the bike.

I replaced It with a 700 x 38C, max Psi was 80 for this tire, I run 75...

The ride is fantastic, No Noticeable speed loss at all as far as I can tell.

On my new 20" folder, P8 I wanted fat tires, wanted the Big Apples, the 20 x 2.00",, I got the 20 x 1.75" and am very happy.
The other one I test rode with 20 x 1.25" was harsh, felt disconnected and every sidewalk crack made it to me...

IMO due to a 20" tire's much reduced circumference Fatter is far more Important as a comfort factor..
As for rolling resistance,, Bha ! Humbug !
How about we get stronger

Loosing 1 mph,,, learn to spin better,
the faster you can spin the more comfortable that next gear is and the less It's like mashing so say's my knee's....

,I don't race so,,,
"I personally would think comfort is more important." ,,, You betcha !