well, no, it is not usable as three independent voices—similar to Just Friends, the only chords you can make are those found on the Span knob (I haven’t dug deeply, but I believe the only “conventional” three-voice chords you’ll find are octaves), but unlike Just Friends there is no Just Type to break out of this shell.
It does make a pretty “clean sine” if you want it too, however, if it’s the timbre you’re concerned about.
If you’re just gonna drool over Three Sisters, it sounds like you’ve already made up your mind 
As for spectral mixing, it is of course definitely possible with (combinations of) other modules, but this is probably one of the smallest “packages” for the functionality in Eurorack.