How do I use non-"legacy" launchctl commands to load and unload plists?
I asked the Twitter user @launchderp:


  @launchderp Arelaunchctl load and unload still safe to use, at least until 10.12 or whatever comes next? 
  
  c.f How do I use non-&quot;legacy&quot; launchctl commands to load and unload plists?


And @launchderp replied


  @tjluoma Yeah they're still safe. Too many years of dependencies to break them.


While this may not seem like an official Apple statement, I believe this person to be someone who is actively working on launchd for Apple, and trust what they say. YMMV.

Moral of the story: If load/unload is working for you, keep using them :-)