Yup, even with my skills, it’s obvious that the total number of bit combinations is the same as the keys in the puzzle. So I’ll probably use this approach when choosing the sub-ranges I’m scanning: start from the previous range, apply the mutagen to that string.
If the key is found before 50% of the 50% expected in random mode, then we can start talking about efficiency.
Maybe they have something up their sleeve that they haven't shown publicly yet—some kind of filtering XOR masks or something more complex that might work. Anyway, maybe it's just a more elegant way to achieve the same thing, though not necessarily faster than other solutions.
It is not faster, it’s actually way slower. KtimesG already explained why.