Incorrect, but reasonable post. LetterBomb exists solely for SM4.3; BannerBomb works on a few SM that are < 4.3 and doesn't require an active internet connection in order to cause a stack overflow (thus allowing for unsigned code to run).
SM4.3 for hardmodders (a rare breed nowadays) prevents out of region playing, whereas you say, for softmodding it's a non-issue.
The best brick PROTECTION you can get (aside from following directions, lol) is Priiloader. BootMii/boot2 is the best brick RECOVERY tool or option you have. Protection and recovery are not the same thing. Certain types of bricks (not full bricks) can be overcome with a System Update via disc or other means. If you're already @ 4.3, there's "nowhere to go" in terms of an update to serve as a method of brick recovery.
There's no added functionality with SM4.3 or 4.2, pure and simply they are viewed as merely further attempts by Nintendo to block what this guide accomplishes (Nintendo will say and for a percentage of the population they'd be correct, for piracy --- but that's not this guide's purpose --- the legitimate ability to play backups when kids tend to break/lose/damage expensive optical discs).