I like the sound, and by sound today, I think of it and like it better on girls, but I find it okay for boys as that is historically accurate. I think now the -son sound doesn't necessarily invoke masculinity because so many of those names have become more used on girls than boys.
Emerson also has the
Em- beginning, so it sounds like popular names like
Emma,
Emily,
Emilia, etc. I don't like the alternative spelling.