That depends on what you want to do with it. firmlaunchhax was patched in 9.3+, so you can't use it to exploit the Arm9 anymore. (at least with the currently known exploit. There may be another one that yellows8/that other guy that has a name that starts with an M but can't spell right now. Don't bother asking them, they probably never plan to release it)
So things like Gateway/other Arm9 homebrew won't work on 9.3 or above.
For things like ram dumping/injecting into ram of currently running program, that still works on 9.5.