When you say Custom, are you referring to the Custom Flying V or a regular cambered Custom? The Custom X differs the most from all the boards you mentioned. I've never ridden it, but it's supposed to be a great board for bombing. It's on the stiffer end in terms of flex, so it won't be as playful and can be very unforgiving if you're not on top of your riding. The difference between the NS Legacy and the Arbor is the rocker profile. NS has their Rocker Camber shape, which is rocker between the bindings, then camber just past the binding inserts and Vario sidecut. The Arbor has a parabolic rocker with Grip Tech. The NS will be a bit stiffer and more damp than the Arbor. The Arbor will be more playful and more lively with the bamboo core.