FYI
The ground staff at Hong Kong Airport Express Station insisted me to pay for HK$200 or US$25 to get a extra legroom seat & I paid for it! But after boarding, the row 31 DE are very nice seats & empty. People in row 32 moved to 31 after gate closed!!!!

on return at DPS, I asked for it & the ground staff put me to 44K w/o charging me a penny! Thx!
Also BIG THX to HK ground Staff!