The new 1.6L engine makes less vibration and sound (this is the first thing I noticed)
Dont rush; only replace if your current car sells fine...People are not getting new car "soon" and you might have to pay "on" or has to wait for 2-3 months! If you are trying to add few more badges on the trunk (SR or Cruisetronic); then I will strongly suggest to "wait" to see how this new car is received in market!
Your car is new; you dont have to worry about anything; enjoy its warranty period and free checkups...I think after a year or so; 1.8L Altis M/T 2009/2010 might sell better than 1.6L Altis M/T 2011!