I know it was already answered but I thought I would go in a bit more detail. Browserhax, menuhax and any exploit that merely launches the Homebrew Launcher are called arm11 userland exploits. They give us the ability to run homebrew, but they don't give full access to the system. From arm11 userland there can be exploits that allow us to gain additional privileges, which are access to arm11 kernel, and sometimes arm9 kernel. Arm11 kernel gives us full access most of the system, but arm9 is the security that prevents us from doing cool things like installing non-legit CIAs. With arm9 kernel access, we are able to bypass these security measures which grants us total control of the system (at least for the average user, there are still parts we don't have access to).
So in order to downgrade, you would need at least an arm11 kernel exploit to have access to title installation. Ninty patched that, but along with it introduced a new security measure via arm9 that prevents the firmware titles from being lower than a certain version. So as far as we know right now, it is impossible to downgrade 11.0 via software without an arm9 exploit, which at that point if we had that it would be unnecessary because we could just update all of the current arm9 homebrew and exploits (like CFW) to 11.0 instead.
