Should be just be careful how you transfer it I normally use a straw to spray it into a clean empty ain't jar then give it a good stir before I put into my airbrush.
James do you use a compressor because canned air propellant can react with the propellant in the rattle can and cause the paint to Bloom
Whenever I've decanted spray paint it's always required thinning a little. That said, I always go by what the paint looks like in the jar. I try to get all my paint to be the consistency of milk,this is of course a rough guide but is surprisingly effective. You should see this consistency in the way the liquid runs from the container sides.
Hope this helps
I think Barry that sometimes the colour you want, if you are doing a car, is easier to get your hands on in a car spares shop than trying to find it "airbrush ready"
And as well both know an airbrush does give a bit more control than a rattle can...
Re decanting. See if the spray top from an old WD40 tin fits the paint can. They have a top that can hold a straw. Remember to leave the decanted paint open to de gas.