With a name like hunter that ends in an "r", having a middle name that begins in an "r" sounds awkward and stilted. The tongue trips over all those "r's"
think about the fact that "hunter" is a very popular uber-trendy name (is there a soap opera character named hunter?) right now and naming your child that will just throw him right on in with all the other many thousands of "hunters" in his age cohort. What will you call him for short? Hunty? Hunny? Do you even go hunting?
Bob is short for "robert", which is a decent name.