The AKC standard now states "not to exceed 7 lbs." Seems the 4 to 7 has changed. As far as male versus female, I don't think females are easier to housetrain if the male is neutered before his sexual instinct kicks in. say 6 mths. Also, females tend to pick a favorite in the house, where males share affection equally. This is just my personal opinion and maybe 2 cents is a little high, but..... there it is
