Smooth cuts on corrugated metal roofing?....

So I did look around at some YouTube vids and websites regarding this issue, but came away feeling that each artisan has his or her favorite methods for cutting (leaving a smooth edge) corrugated metal roofing.  I've used tin snips and electric shears (nippers) with fair results, but for smooth edges am looking for opinions and alternatives.  Among the various approaches suggested are a circular saw using either a blade designed for light metal cutting or a regular wood blade turned backward in the saw.  Additionally there were suggestions of either a circular, jig, or reciprocating saw using a blade with diamond grit as the abrasive cutting edge.  Anyone having worked with steel, ribbed roofing with an opinion on what worked well for them would be appreciated.  Thanks....

I would use an angle grinder or 7" grinding/cutting disc in a circular saw.  Just make sure to secure your work pieces so it doesn't bind up or go flying.

I use a small circular saw with a special metal cutting blade it's made by Hilty and my neighbor lets me use it when I need it otherwise I've had good results with the angle grinder and a cut off wheel as well

Ditto for Thomas' & Ray's suggestions. A metal cutting blade in a circular saw will work the best as long as you don't get the blade in a bind. Wear adequate eye protection (well-fitting goggles) because those blades throw a hellaceous shower of sparks. I can tell you from first-hand experience that a trip to the E R to get metal fragments dug out of your eyes is no picnic.

I too have had a metal sliver lodged in the eye,AFTER taking off my goggles-it was perched on top of the goggles!
Since then , full face shield is my goto.

An angle grinder wiped with a diamond wheel will cut metal,and not throw off abrasive dust, so I prefer it.

Thanks for these replies so far.  Looks like I will probably look into a cutting wheel or a metal-cutting blade for my circular saw.  Fortunately, I have access to some full-face shields, and after hearing your stories will definitely be using one.  There will only be a few pieces to cut, but I wanted the edges to be straighter and smoother than my past efforts with the nibbler, which does an adequate job, but wavers over a long run of cutting.  Grateful for all of the expert experience and advice on this forum.....

I've worked with corrugated metal roofing on several of my projects. I've always had success using a circular saw with an old blade on backwards. Works great.

We have used plain wood circular saw blades put in backwards.  Fairly course tooth plain steel blades not carbide tipped as the carbide running backwards is torn off and become projectiles.  Works well on heavier corrugated roofing but modern light siding steel it produces a bit of distortion.  Big advantage over abrasive cutting is the steel stays cool so no burning finishes or plating off.  Edges are fairly smooth with a few tiny flakes of tear off attached.  Fairly clean and fairly easy to clean up with a sander.  

I always use a circular saw. I have tried a jigsaw and reciprocating saw. Perhaps if you had clamps to hold it down it wouldn't be as absolutely insane as it was when I tried. The flapping. AAHH!! Although I did cut a hole in our barn siding with the reciprocating saw and that worked just fine. I suppose stability is key there!

The safest electric tool to use is a NIBBLER.

They come as a drill attachment or a stand-alone tool.

It leaves a neat, clean edge.

Importantly, the nibbler can be used for fancy work on sheet/corrugated metal.