Unlike most conversion notes, I will begin by explaining what is wrong with virtually every game system conversion method that I have ever encountered. These methods, especially in the superhero genre, indulge in one, and sometimes in all three, of the following unsuccessful mistakes:
This is doomed to failure. Indeed, anyone with real knowledge of the games in question would immediately see this by comparing what each game considers to be a "normal human". There are no two game systems on the market that give the same "real world" abilities to an ordinary human being. If the games can't agree on that single point, why presume that their "real world" to game system conversions would be compatible? Game systems are designed, first and foremost, for internal systematic consistency.
This is based on the unwarranted, and invariably false, assumption that all game designers put exactly the same relative cost on various abilities in a game. "Conversions" based upon this paradigm include infamous "Every AD&D level equals so many GURPS character points". It just doesn't work. First, these methods presume that the "balance" of one game's systems is identical to the "balance" of every other games' systems. Second, these methods presume that the implicit and explicit character design emphases within each game are identical. Both presumptions are, of course, false.
The most intractable error of most of these conversions, though, is that they forget a simple fact of music: A trombone is not a violin. A violin is not a French horn. I sometimes wonder if gamers are aware of that little detail. What has this to do with conversion notes for a game? I can take a violin concerto and try to get a French horn player to play it. His lips would probably implode from attempting to get such high notes. I could do a simple-minded transposition down however many intervals is necessary and claim that it was sufficient. Neither methods really would work. What has to be done when changing a musical piece from one instrument to another is to understand what will and will not work for that instrument. The fact that a French horn cannot glissade does not mean that the violin should be prohibited from the glissade if that is what really works in the violin version. Likewise, the chroma of the French horn should not be neglected simply because the violin has a different sonority.
An example of this error in games is in an old DC to Champions conversion. DC Heroes does not have the END mechanic as the default. Therefore, the conversion very simple-mindedly stated that all DC Heroes characters should have their powers bought with zero END cost. What the author of the conversion simply did not realize is that in Champions, zero END is not the norm. Paying END is part of the paradigm of the game. Therefore, to truly convert a character to Champions, a character with a normal DC Heroes power generally should pay END in the Champions version--because that is more true to the Champions paradigm.
The whole point of this essay is to explain why the converted Champions charcters might not function "exactly" like they would in DC Heroes. Rather than try to make "exact versions", I have used the DC Heroes originals as the original composition wherefrom the Champions "arrangement" could be derived. My methods were not arbitrary, and there was a system behind it. I just haven't written that system up.