The mantic is much cleaner if that makes sense its not got the bit of hair to it that the meatbox has.
sadly to my knowledge the density is the only similar pedal, octave downs just dont do the same thing however you could try an octave with a eq pedal to trim out freq you dnt want and just grab the MB one i believe 30, 60, and 90 hz but i could be totally wrong on those numbers.