Fiddled around with my RotF Jetfire for the first time in months and its batteries were dead, so I replaced them. No leakage from the generic Hasbro AAs.
This prompted me to check my other older electronic movie toys, which all have their original batteries. No leakage on any of them, although my '07 Brawl's batteries were also dead. Despite being roughly the same age as Jetfire, RotF Megatron's batteries still have power.