Right on Chad, you have made a good case for N2 in your tub. As long as you can extend the FC residual with less frequent dosing, that's a good thing.
SpaNE,
I think there are a lot of factors that go into this equation. It can depend on how much dichlor you put in for each dose. It can depend on how much you use your tub. It can depend on how many people use your tub and (seriously) how clean they are (do they introduce a lot of bacteria into the tub).
The bottom line I think is that commercial spas are required to maintain a minimum FC level at all times, that's what keeps your tub safe and can be easily measured so you know your tub is safe. So that's what you should strive for with your dichlor dose, whether it's twice a day or once a week.
Regarding MPS, it's an oxidizer not a sanitizer so it is good for removing combined chlorines and contaminants from your tub. This is typically needed weekly for your shock, not daily.
Plenty of folks use this routine with their N2 and Ozone equipped tubs. The N2 and Ozone provide what is called 'supplemental sanitizing', but your dichlor is your primary sanitizer.
Steve