I'm conservative and play safe. 500sqft is not too big to start with and when u familiar with a smaller place u no longer feel it. 1800sqft is not that small. Small difference in size potential big difference in the future. Since location is the same no comparison of LH in a great location because both are. I prefer to look at other details ie assessibilty, feng shui (personal opinion) and if can surrounding neighbours becoz you not only buy a house but also a home.