We are blessed with such a beautiful place called Malaysia to be precised Peninsular of Malaysia. The condition here is suitable for White Nest farming as the the number of black Nest (maxima & collacalia) is lower compared to Sarawak and Sabah. Most farms here attract only the Aerodromus fuciphagus, where as in Indonesia and East of Malaysia the farms there are occupied with also the black nest. This is why in Indonesia cross fostering technique is being implemented in most areas.
So in general all areas in P.Malaysia are suitable for Swiftlet farming ,even in the heart of the city.The pictures showned here are in S.Alam. Some are already started harvesting.
I believe if its done the correct way everywhere is a good place the only set back is time factors and quality of the nests. Of cos with good vegetation around the quality of the nests are better. These farms here really impressed me as most are very well camouflaged. One may not noticed if you are not into this field. 
So the whole differences are, doing the correct way and doing it because the trade is lucrative. I would rather choose the first.