Fei Mau Kor,
I can only comment on 20 X 70.
Car Porch do not have any gardening, they only provide homogeneous tiles. Perhaps, they want to avoid ppl from growing cili padi or betik? And at the same time enjoy their 10ft backyard garden.
There will be mechanical ventilation for bath 3, but SA couldn't answer me when I ask how they run the flexible duct since they say they won't provide plaster ceiling.
The height of each floor will be 11 ft which is pretty high.
If not mistaken based on the House Model, I did saw a hollow section from the top. Meaning to say, there are windows for both Master & Bath 2 ( double volume ).
Saving space for the Bedroom 2 & Bedroom 3 is a good point. However, due to that there is only 2 bathroom compare to the 3 bathroom at the 22 X 70. Perhaps small family do not like to have too much bathroom?
The rest of your points I'm quite agree with. Just my 2 cents.
I was told they are using GI duct and to be camouflaged with beam to discharge at external wall. No flexible duct.