A little more testing....
I left the bike on the main
after the low fuel light came on this time(needle on E), and rode normally. I got another 10 miles before I went over a railroad overpass. At the top, I got a stumble, so I switched to reserve. I rode down the other side of the over pass, thru a light, and turned into the filler up spot. It took 4.1 gallons to fill to the ridge at bottom of the neck.
I'll pick my route more carefully next time so I can run further on the flat, to see just how far I can get on the main.
Based on this stumble, I think the original stumble issue, was just fuel level in the tank.