I have to say that I was very very sceptical about this when I saw the app in Play store, claiming to be able to disable lock screen.
it actually WORKS, and works JUST fine. Tested on HTC One with 4.4.2/Sense 5.5.
At times it works a little TOO well though, like when you restart your phone with NoLockScreen activated, as lock screen is being used to open up your sim by entering sim pin (if you have used that function). That means that the lock screen being used to open up the sim is killed, your sim is not active. But, just enable the lock screen and it works.
Haven’t used it long to know if it drains extra battery, but it doesn’t seem to do that. For me it just works.
You have a widget with it as well, to make it a bit easier to enable/disable lock screen. It says in settings that disabling notifications for it might make it unstable but haven’t seen any problems from that yet.