Connemara is a breed of horse. I would not use it as a name. Even if you were to use it, it sounds much more feminine.
I do know a boy named
Shea, and he's quite masculine, so I don't think the name really has a bearing on that. I also know a girl whose middle name is
Shea (
Leah Shea), so the name is unisex to me.
Overall, I do like it a lot. It's short, elegant, and a great alternative to some of the other overused one-syllable names...
Lee,
Lynn, etc.