Unfortunately neither really achieve my aim. Carp::Assert will break out of the running program if the condition fails and, if your running under -d, then you'll end up in the debugger. The problem is that you cannot then continue the program or even inspect the state that was in play when the assertion failed. It in no better than  die if .... in this respect.

Devel::StealthDebug is basically print statements in comments enabled or disabled through a source filter. A nice idea and implementation, but it doesn't achieve my aim.

I'll update the OP to make this clearer.