The Sidekick I believe has the 24" barrel and the Huntsman has the 26" barrel. They are almost basically the same rifle except the Huntsman can be sent back to the factory and fitted with centerfire barrels and shotgun barrels is my understanding. That is why it falls under the stricter mailing codes and needs to go to a FFL holder in the United States, where as the Sidekick in many states can be mailed to your door.

http://www.dallastacticalsupplies.com/itemdetails.asp?itemid=NESPS050

I personally have no first hand knowledge of their loads, but they should be very similar in nature. As for performance, they should also be very similar. The deer you shoot with it will never know the difference...