I think that either name would be nice for a boy! I happen to be a male Kelly myself, and Robin is a "semi-favorite" of mine for a boy. (There are numerous other "boy-turned-girl" names that I like for boys as well.)
I have an ex-uncle Kelly and my mom is Kelly, so it is sort of an ambygous gender for me. Thanks for your input. I always wondered what a male Kelly thought of their name.