Originally Posted by FlyMan
They will put you on a waitlist if no seat in the Superseat Premium is available upon checking-in. But if you are *A Gold and check-in about an hour before the flight, your upgrade will most likely clear. Speaking from my experience...

Thanks for the information. Does one have to pay for the superseat? Or can one get a free upgrade (since these are actually C tickets except booked in Y for this segment).
Slightly off topic, but if I get to the airport a little early will NH allow me onto an earlier flight than the one I'm booked on (I do know the * rules about changes once travel has started) but thought I'd check.