I have to say that my own experience over the last two years matches burntsusih's pretty close.

In the case of logic stuff Tagged Union/Enum types help me force logic at compile time. If I've got a particularly intractable logic problem a good coverage of unit tests works well to flush out any bugs and give me confidence when it comes to refactoring.

There's been a handful of times that I've wanted to reach for the debugger but a couple inspect()/println!() calls did the trick in those cases.