alt Hacker NewsThe Steinberger TransTrem [1] similarly allows changing pitch at the bridge. Buck Dharma and EVH used it to great effect. It's about as simple as a design as it can be but calibrating it is a process and guitarists aren't exactly a group known for their engineering prowess or progressive thinking (compared to bassists or keys players, for instance) so it never achieved critical mass. This seems like an even simpler system so perhaps it'll gain greater traction.
TransTrem doesn't allow for single string pitch changes though, it's more of a solution to easy alternate tunings when you have a whammy bar.
A simpler solution is probably using a crossover or synth-pickup so you can split the bass notes to a pitch-shift pedal.