Complex VCOs are just as capable of doing ambient music as they are for creating gnarly, raucous racket. The deciding factor is simply how you use it. The nice thing about them, though, is that you can easily whip up complex spectra within one module...which was something of a key thing for the Buchla, which is where the complex oscillator idea comes from. In Buchla's synths, the main working method was to build up complex sounds, then run the results through a low-pass gate, basically a tandemmed LPF and VCO under the same envelope's control.
Anyway, the upshot is that you should be able to use a complex VCO however you see fit. The Buchlas were just as capable at creating delicate, atmospheric sounds as anything else, but the architecture allowed you a little "more" in terms of working with the sounds in real time.