most bag targets aren't real portable.
I disagree, you can make a stand out of PVC pipe and carry it pretty easily....with or without the stand. There are small sized bag targets that are much more easily moved too.
The Cube is a good broadhead target, but pulling field points is a two mule affair....with carbons that is, I've never shot aluminums at it, so I can't say as far as that goes.
I have no experience with the Block or Black Hole.