RE: PA mini Katana vs ExtremeFlight Extra
Those planes are in two different classes. Both are 3d capable aerobatic planes, but one has a 45 inch wingspan and an empty weight around 18oz, the other is a 40 inch wingspan with a 13oz empty weight. 5 inch extra wingspan and 5oz heavier airframe bumps it up, not quite a parkflyer anymore (though i would gladly fly one in large parks)
I would compare the pa katana mini to a eflite mini funtana, a mini edge or mini extra by fliton, there are so many others in that size range... The extreme flight rc is in a class all it's own, there are few planes in that size range that are designed to be electric from the ground up.
Though i have had neither, i would probably lean towards the extreme flight extra myself, because of it's large size. I spoke with extreme flight rc officials and that's where i got the 18oz airframe weight figures, this means it is possible to end up with an auw well below the advertized 30-33oz when using high efficiency motors and high energy density batteries. Both these planes get great reviews though and you will likely be satisfied with any of those two.