Joshua, thank you for posting this idea at
http://ideas.x-cart.com/forums/44381-x-payments/suggestions/3055746-option-to-only-charge-decline-a-transaction-when-c
I hope other users of X-Payments will find it useful for their business processes and vote for it at the aforementioned link.
NOTE: Please vote for ideas carefully as we won't be able to implement all of them at once and will select the most popular ones.