Yes, it is unsound. Quantum mechanics has features which aren't observable (the imaginary components of the wavefunction, the value of position and velocity at the same time, etc). However, this does not mean less computation, because in order to simulate the system you need to represent the whole wavefunction and everything that happens to it whether it's observable or not. Quantum mechanics is elegant in many ways, but low computational load is not one of them.
Is it weird that the complexity gets me excited? The thorough needs of this kind of nature of computation is a thrill to dream about.
Thanks for the notes and the links. I've recently started to work my way through Feynman's lectures a I'm considering a return to school for physics particularly because of the excitement it brings me to be able to even just peek beneath the covers. I want to be able to rip them off the whole damned bed and leave the sleepers exposed! But I digress...
See Feynman on the subject: https://people.eecs.berkeley.edu/~christos/classics/Feynman....