It's not as big a deal as if you were checking in to one of the larger resorts, but if you do the online check in your stuff will be all ready for you so it is a bit faster. Don't do it if you want to request a certain loop, though. They will pre-assign your cabin and have your keys made if you do it online.
They have a separate line for you to pick up your envelopes, but the check in area for FW is so small it doesn't save you all that much time, IMO.