Note that after being turned into 86J or refurbished then the power sockets will turn into USB (and multi adapter AC socket in WTP and above). It's just the 52J unrefurbished that have empower in WTP, and I doubt you can be certain they (a) will work and (b) what aircraft you will get beyond the next 3 days. Moreover unless you are travelling a lot in countries which use elderly cast-off aircraft as a matter of routine, I suspect any Empower adapter is heading towards a museum. If you do buy something it would perhaps best be a pre-loved device rather than spend too much money on it.