^^ To be honest, it was mainly from the days when people didn't use overgrips. There was something about a Fairway grip that made it feel so much better in the hand; level of tack was pretty much perfect, regardless how sweaty your hand became.
With an overgrip (which is how I use it now), you'd be hard-pressed to find a difference between them and another quality leather grip. I can just about spot the difference between a calfskin grip and 'regular' leather under a Tourna Grip (Head Finest Calfskin is the most supple I've used), but you'd have to be really sensitive to strongly favour one brand over another. The main differential now would probably be thickness, and whether you'd want to make your grip fractionally smaller or thicker.
My String Journey: http://tt.tennis-warehouse.com/showthread.php?t=362403