Which is good
One could argue that Jumbo Cactuar is not broken at all, and that there are already some very powerful cards that can single-handedly win a game even without 10,000 power, and that is true
It has great flexibility as a midrange commander
It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or any Auras or Equipment attached to it, or any non-copy effects that have changed its types, color, power and toughness, and so on
Having tracking information and insurance will ensure that you will be taken care of, no matter what happens
If Ephara is the breakout card at a Grand Prix or Pro Tour soon, she will double in price, and you should buy in once the decklists start hitting the net