I've read a lot of reviews that talked a lot about matching Cartels with the Custom X. I hear you need stiffer bindings to get the most out of the Custom X. But if you're getting a new board, I don't think you'll be happy with anything that's not at that level of play (the Custom X).
I read yesterday in a review of the Custom X, once you know your board is limiting you vs. your abilities, it's probably time to get a Custom X - something to that effect - of course not for freestyle.
Anyway, I'd check out the EST Cartels. I have the green ones and they're a bit stiff, but I love them (matched with a regular Custom), plus down the road you'd probably want to get another X and those are now getting the full ICS treatment which you could take advantage of with the EST bindings.