I’m 6.3” and sat in row 4 on a NEO last night for the first time - It was fine for 2.5 hour flight, with probably 3 hours spent in the seat in total. It is worth noting people at the very back of the plane may spend about 20 mins more in their seats at the moment due to the way boarding and disembarking is handled, so the further forward the better at the moment in my mind.