I love that hand metal cutter thingy. It cut through that sheet metal like butter. I once tried doing something similar with a jigsaw. It did not cut like that! Having the right tools makes a huge difference.
I love the channel, it's my favorite. It's hard to stretch next to a brake (body line) in the sheet metal, the tension in the streched metal can not over come the edge and will cause oil canning. You can E wheel the slight crown in the panel then put the body line in after, with the E wheel using the upper to create tthe body line by pusing up on the panel while moving across the panel. I know you guys probably know this alrady, so many different ways to do metal shaping for the same panel. I just wanted to give my two cents for the other readers.