We've have had leveling issues in the past with our brand new aerial, so I'm very familiar with the operations and benefits of the device. For firefighter safety I don't see any reason why you would use the aerial without the self leveler activated? If no manning is on the platform, you could always adjust the nozzle and waterway direction despite the platform level. In my opinion the self leveling option should always be activated.
There are different methods and ways to perform rescues and use it to its full advantage, without requiring the self leveler to be disengaged. Cheers!
" When the elevator doors open, if it's hot...dont get out!" - Lt. Steven McCaffrey