I know my situation doesn't fit your query but I have the reverse: Large gap between my first and second then a small gap between my 2nd and 3rd. This was kinda planned and works really well on the whole. Our 1st (DD) has said that she feels that the younger boys get all the attention now but I think you would get that to a certain degree anyhow... and it's just that she gets a different kind of attention.

A lot depends on how YOU handle the dynamics. I think with the right approach almost any combination of gap, genders etc can work in a loving family.