I highly doubt anyone in a normal house is going to have a single device that can take advantage (or need) the 500mb and 1gb speeds but if you have numerous users you may be able to take advantage of it.  I have fiber that provides 100 down/50 up at home.  Our ISP recently upgraded us to it from 50/25.  I can not tell any difference except when I download something large such as an operating system ISO.  My network can handle gigabit speeds but internet browsing and normal activities don't need it.  I'd probably still go with the 1gb because its an insignificant price difference.