it hink it is fine. i threw a shower for DH's friend and his gf and cause we didnt really know her that well it was more of a manly baby shower lol. there were about 30 people (male and female) we still played games and the guys got into it more lol.
its up to you and wat u feel comfy with. i had a girls only for my first and had about 15 ladies and then my 2nd my exSIL threw for me and there was only about 8 people but that was only because alot didnt show up.