Stu, your theory sounds great, but if I were you I would stay away from Marine. Lots more work and it's not quite a case of putting in additives and waiting for Nitrite to disappear.

For one thing you will rarely have an Aquarium with zero Nitrate, once it has completed its biological cycle. Well, tap water has a fair bit of Nitrate in it already, so you won't do any better than that unless you use RO water.

The Ammonia/Nitrite/Nitrate levels are a constant balance of how many fish you have, how you feed them and how good your filtration is. A dramatic change in any direction and your fish are brown-bread etc etc.

Stick to Tropical IMO.