though it is an automatic inflatable
Is that a sensible idea
Think about it, you ditch and the aircraft starts to sink with you in it. The LJ auto-inflates whilst you are still inside the aircraft. One of the main reasons why you do not inflate your LJ inside an aircraft is that if it is filling with water then you will float to the top of the cabin and struggle to get out.
It has happened. In one accident off Australia (I think it was) all on board survived the ditching but those that ignored the "do not inflate your LJs until outside the aircraft" drowned inside the cabin because it was filling with water, they floated to the ceiling and could not get out. All those that did not inflate their LJs inside the aircraft survived!