Heh Dave...
I ended up getting a bit of experience with these tools while rebuilding my truck, and later putting metal siding on my house... just a rookie, but here's my take on them.
Each tool is great for some things, horrid for others, each has their purpose.
Air Nibbler - Amazing tool for cutting, steel must be fairly flat, leaves a ton of cresent shaped filings everywhere, works best for cutting tight curves (although with a straight edge, it can be kept in a fairly straight line). Great tool, yet limited usefullness. Used it for trimming off new panels to match curves of previous rusted parts, nibbling away the edges and basically making new pieces of metal match up after they were roughed out.
Not the greatest pic, but showing a curve that worked great using these.
Air Shears - Awesome for cutting straight lines with, so smooth it feels like you are cutting paper, yet they remove a 1/4" or so of material where the jaws intersect. They will do slight curves, but don't handle ridges very well. Like them better than aviation snips as the two outer jaws keep the material from bending, the middle jaw just pulls out the cut material... smooth edges afterwards. Used this on new sheet stock, for making new panels and such.
Air Body Saw - Another amazing tool, cuts through body metal like a hot knife in butter, but vibrations in the hands... wow. I liked this one for smooth freehand curves, yet only used it a bit due to other tools being smoother and doing the same job. Also works fairly well on surfaces that aren't smooth. Used this for floor pans, cutting out rust in tight areas, etc... pretty much like a mini-sawzall, but a heck of a lot smoother.
3" Air Angle Grinder - Awesome for cutting with freehand, but edges of metal had to be smoothed more than other tools (i.e. burrs filed down later). Great for ridges and metal than wasn't soo smooth. Used this for cutting out rust, working on the floor pan, etc...
Aviation Snips - I'm really hoping you have these in the tool box as well?
Ha... they are great for fine tuning things, quick to trim things up that don't just fit right, and besides the cramping in the hands when used for too long... they are a tried and true tool that can be used for almost anything.
Metal Bandsaw - K... now I'm way off topic... but dang, it'd be soo sweet for cutting out parts and fabbin' new metal up. Not good for working on the vehicle, but prior to... Oh well... next on the list.. :thumbup:
Anyhow... just a rookies' take on some tools...