Weight and size is a factor with installation and winter storage 

size is a factor if i were to store it. have minimal closet space. most people leave them in year round. my other one is screwed into the metal framing around the window. only problem with that is potential draftiness in winter as the window is near where i sleep and is already a little drafty. also would preclude using window fan on nights when a/c is not needed. theres another window but opens to fire escape which means apt is less secure. i read fans in a/c which are loud and dont really work that well use a lot more power than normal ones.