Well theres no real difference between Pro Logic and what you're doing. You're taking a 2 channel source and asking a DSP chip to 'make something up' to send to the other 3 channels. Those channels did not exist, they were electronically created..just like Pro Logic.

And don't get me wrong, that's fine if you like it but calling it 'natural sound' is like saying Pamela Anderson has 'natural boobs'. It's about as fake as you can get