I agree with Nathan that two kinds of fire forming are being discussed: Major and minor. Major would include feature changes like different shoulder angles and bullet diameters per some of the calibers mentioned. Minor would be forming the 300 Win Mag to headspace on the shoulder instead of the belt or the 303 British to headspace on the shoulder instead of on the rim. In between would be the less dramatic reforming of a case to its Akley Improved version. I think Sharpsman's method is fine for the minor, and the AI cases have long withstood simply firing the commercial parent cartridge loads, so I suspect Sharpman's method with a 10% reduction in powder to allow for the jammed bullet's effect on pressure would likely work for AI as well.
For major reforming, you run into the issue that few cases are formed with perfect brass thickness symmetry, so if you expand them with too much rapidly applied pressure, the lion's share of stretching can occur on the thinner side, exaggerating the difference, work-hardening the thin side and thereby setting up for splits to occur. The COW method works by pushing the COW through like a fluid extrusion die, slower and probably for reasons to do with not applying too much radial pressure initially when the pressure is at the back, does not tend to result in exaggeration of non-uniform thickness, which is its major virtue.