Thanks guys. I just sent money to a member here for a Terraframe with removable bag.
Prez- I think for most, if not all, of the models there was a mixture of ability to use the frame without the bag. For example, there is a Shortbed on eBay right now that you cannot use without the bag because the load lifters are sewn to it. There was also a Terraframe on there not too long ago that was the type where the bag couldn't be removed from the belt. I apologize if using the frame without the bag wasn't what you were referring to as pretty rare.
rider- I am familiar with MR as I had a Crew Cab and currently have a Longbow. I want to give an external with load lifters a whirl, rather than the Lift Kit available for the NICE frame, and see how I like it for hauling meat. From what I could find, the Dana external frame is consistently well-liked.