I do use mixcraft 4.5 myself.I do not know much about the editing software you are using.I also bought and use the Jamstudio loops:
http://www.jloops.com/index.htm jamstudio's music factory is made up of 2 sec. 16 bit WAV loops and will work with just about all editors.If you are going to change the pitch do so at the point where the loops meet.Your key changes should be at the point where the loops meet.I have uploaded a pic to show you how the loops come together.
