Taking this logic to an extreme, you could have complete control over your safety margin by referring to, say, a table rather than a computer. As you put it, "If you want to run close to the edge ... you can." Just dive to the very limits of the table. Or you could just as easily make your dive as conservative as you want.
For all the people who say Suunto is "too conservative," I say then go use a table rather than a computer and feel free to stay down as long as YOU think is "safe."
actually, your logic is severely erred...
a table is even more conservative than, say, a Suunto...
All computers use an algorithm that has been tested to be safe. Pelagics, for instance, are more liberal than Suunto's. If I am diving a Pelagic, and it says I have 20 minutes of NDL before I run into Deco, and I want to ascend to be a touch safer, then I can, or, air permitting, if I wish to stay longer, I can, without penalty by my computer, and still be reasonably assured that I am safe (thousands or millions of divers use Pelagic computers for thousands or millions of dives and I've never seen a report showing that they are more likely to get bent). If I am diving a Suunto, I may not have the option of staying, and be required to surface, or face a deco obligation. This is how I get to choose and set my own conservatism on a liberal computer.
Tables are the MOST conservative, and sure, you can be more conservative, but you can't be less, for sure. If I do a dive to 52 feet, I calculate that as 60' on my tables, which gives me 55 minutes NDL. That is already a very conservative factor, yet if I want to stay even more conservative, then I don't spend the whole 55 minutes, simple as that.
No where in any of my examples do I suggest staying longer than your computer or table is happy, I only suggest that you can make your own computer more conservative than it is simply by using your brain, rather than being completely limited by the conservative algorithm embedded in your computer.