Lately ive been playing with keepinventory and hard difficulty to balance a bit. I like the flow of the game this way, i just wish i lost my exp on death as a penalty.
I do this too. Losing my stuff just irritates me and doesn't add anything to the game(IMO), so I tend to use keepInventory just so I don't end up ragequitting when I slip up. Plus I tend to be more adventurous if I can die without losing anything but my current location.
Aside from that I tend to use little things to save time, like setting it to dawn if I'm mid-project but "safe"(IE : By home). I've also cheated in things to test functionality(or just to see how they look, like various lights) before throwing the spawned items away.
Also : Man up people, if you're spawning in stuff or changing the rules, it's cheating. Sandbox or not, Minecraft survival mode is a game with clearly defined rules and expectations on how it should be played and no amount of semantics or arguing will change that. Nobody cares, so just wear your cheater badge with honor instead of trying to debate your way around the facts like a politician.