My main house is the only one I paid off because I was expecting some kind of achievement for it. It was a let down to only get free house customizations for free for paying it off (especially since there aren't enough options for customizations IMO) but I gladly paid the fee for the extra storage. I have had to clean out my storage so many times because I ran out of room, and I have two other characters and use their storage as well. It is nice to have the extra slots...would be nice if we could keep buying 800 extra at that price as many times as we wanted with no cap.