Be aware that there are two major versions of Optiboot out there. There is the version included with the Arduino IDE (and used on the Uno), which resets the WDT early in the boot cycles, and thus does not have the "bricking" problem.
There is also the latest development version (most easily obtained in .hex form via The MCUDude Cores, which also solves the bricking problem, but has some other new features, like passing the "reset cause" to the application.