I think the electric setup really boils down to how you want to fly it. standard aerobatic and sport flying would be fine with less and more 3D type stuff will need something more potent. I'm not familiar with the recommended setup so I can't really say how it is.

I think I'm going to order a YS-63 for mine. No reason really other than I've never owned one before and figure I'll try it out. From what I've seen it should power the Extra very well.