This is an interesting thread. I don't mean to offend anyone but it seems like people who don't check bags and carry on only want those who do check bags to leave as much space overhead for themselves. Someone like VegasGambler has taken the time to check his luggage and requires less than average OHB space seems not to deserve ANY overhead space in the eyes of some. Does not seem fair.

Totally separate note, I thought UA had redesigned the bins so that all new planes and retrofits can take one standard rollaboard per passenger in the OHB?

I have never heard from anyone at United that only rollaboards can go in the OHB or have first priority over anything else. There are some awfully big backpacks out there and my rolling computer bag ain't small. The FA announcements are about "smaller items" and coats going in last.