Please refer to the new king of modulation, the strymon mobius 8)
http://www.strymon.net/mobius/
As to the L6, i cant offer more info! If im not mistaken though, this needs its own power supply, an AC plug, not DC like all the rest!
accoording to its manual, 9VAC 1200 mA minimum. So it pretty much needs its own dedicated power supply.
And even in its own family, the L6 M9 can do more than modulation, and i would think its in a better position than the L6 MM4. Update-able, newer, better support etc.