This is an excellent trick, although the direct conversion should give equal results! With both, at least one mapping will never make it, the glyph that should be mapped to character $F0F0. This is because Macintosh Roman codepoint $00F0 represents the Apple logo and Apple has a trademark on it.
enStep created hundreds of fonts which were messed up! For each name they perhaps “appropriated” a font and made an extended version (probably taller) and one they call -3D which has an unreadable 30-40 degree italic angle. They published these two using the same name (e.g., IDEA.ttf) – even though there were wildly different designs. They became duplicate fonts in my scheme of things.
So my problem has been to differentiate the two versions by renaming them and fixing the platforms. Glyphs at the end of the font (from Scaron on back) are not mapped, even though the PostScript names are there. So when I “Change” the maps those unmapped characters remain unmapped.
My solution thus asks for them to be mapped to the Post Script names. It may have specific application, but it seems “fool proof” for any font as long as the postscript names are straight.