Cailin seems too close to
Caitlin to me, if you're trying to get away from it.
Caitlin seems to have more staying power, while
Cailin seems simply trendy.
It so happens that the two Cailins I know are boys (Caylen, Cailen), so I tend to visualize a young boy.
I don't think it sounds uneducated, but I do think it sounds trendy and will be overused and dated soon enough (at least in N.
America). That said, there are worse names.