I love our new Chief pneumatic shears for cutting metal

This is the first time I have used pneumatic shears and my eyes have opened. What a great tool! Makes cutting sheet metal, flashing, roofing materials, and hardware cloth a breeze. No more wonky cuts with metal snips, repetetive stress cutting wire mesh wire-by-wire, or knuckle ripping -- your hands stay up out of the way of the sharp material edges. It does remove a 1/4" wide strip of material, but the cuts are beautiful and so easy to do. Wish I would have gotten this 10 years ago.

Harbor Freight Chief pneumatic shears

I don't have a pneumatic pair of those but I do have a nice electric pair. Mine are more of a nipper than a sheer they don't peel off strips when you cut with them instead they take out really tiny crescent Moon shapes as it cuts across this does have one advantage and that is they give you the ability to make intricate turns corners and fitments without ever having to stop, back up or make multiple cuts for tight corners.  They also are low energy so I can use them out in the field off of a 300w Inverter that I keep in my Jeep/ pickup (Whichever I'm using that day for working)  but ou're right,  they are absolutely wonderful and cut hours off your day when you're doing a full metal roof or building.
Once you get used to them you can even end up with some beautiful edges without anything but a pencil line to guide you.
Both the p pneumatic and the electric ones have the ability to cut through metal that is three times as thick as what you can do with hand shears.