Putting Missions on a board like the NS SL? I'm sure you are committing some type of snowboarding sin there.
Ride Contraband Snowboard Bindings 2010
I'd take these over Missions and Cartels personally
Burton Cobrashark Snowboard Bindings 2011
These will be great for your riding outside the park. You can also adjust the flex of the ankle strap on the fly for those park runs in between
Ride SPI Mens Snowboard Bindings 2011
We don't have this next suggestion in Large, but you should look around for it as it will be a really good binding for you: