Oh thats awesome about not having to open up a port. I saw it was added but didnt know the advantages of it so i didnt bother getting it. Ill definitely that now.I use CrazyRemote too. It's really good.
And now that it supports Google Accounts, you don't even need to open up a port on your modem/router to use it outside your home network (aka with 3g/4g).
Haven't tried Slapshot though.