Just booked exit row on a 737-900. It's just not a worry at all. Now, would I sit in row 29 or 30 on Delta's 737-900? No, but that's because their -900 economy section has awful legroom, and the plug at those rows messes up the window spacing to boot.
That said, I hold some thin reed of hope that Boeing has so screwed up the Max10 certification timeline that Delta gives up on their disappointing order of 100 copies (UA has publicly said that have no confidence of a timeline for delivery of theirs). The Max10 I expect to be another uncomfortable sardine can.
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