In the late 90's(97-99) I moved down to Miami(South Beach when it was cool) to live from Dec-April and back up to NYC from May-Nov and working in both cities. I had the best time in my life during those years. To me its the ideal NYC is best in Spring and Fall and Miami is nicest(or it was) in the Winter and early Spring.
The Summer in both places can be hell at times.
To be in one place the whole year round can wear you out. If i were you i would see if i could swing it. Have a house in one city and an apartment/room in another. That way you can still be in touch in NYC and not lose contact.
Can definitely be done.thumbsup