I would like to begin by expressing my fondness for this name; it is a delight. My first experience and introduction to it was meeting a Kerry Blue Terrier (a dog) bearing it.Having said that... unless the person is of Irish descent and possesses a surname of identical origin to balance, "Fionnbharr" will regrettably not work well. With this particular spelling, the pronunciation is an immediate factor-- but my reason is more closely related to the fact that it will appear "self-kre8ed" in English-speaking countries; it will appear that you are trying too hard, and thus is rather pretentious.