No difference in shooting - the more grooves there are, the narrower they are and the more quickly the throat wears out - supossedly - this is important only in very high velocity small bores, like the .17's - some say their 3 groove Pac-Nor & Lilja barrels last longer than the 4's and 6's from the same or other makers.
In the larger bores - probably no more difference that what Mike noted.