I called HSBC Infinite card hotline at 1800 227 8811 and this is what I got.
Local Spending:
first year 1$/1mile
Second year is $1/1.25miles if spent more than 50,000 in 1st year
Second year is $1/1.5miles if spent more than 75,000 in 1st year
Overseas spending :
First year $1/2miles
Second year $1/2.25miles if spent more than 50,000 in 1st year
Second year $1/2.5miles if spent more 75,000 in 1st year
and if you qualify for the earn ratio increase from the second year onwards, it continues till T&C changes.
unlimited one way transfer to the airport if you back it with any 1 transaction. The unlimited transfer IMO, the most worthwhile as I stay in the west.