I think the current freeware models are enough detailed and framerate friendly for the present hardware. It means, the number of polygons that a model have, and those so much MByte textures are well fitted for our current PC-s.
I think the final quality of a virtual aircraft depends mostly on the repainter. It is useless to have the fuselage from 8 pieces of 1024x1024 pixels sized textures, if it consist of big 1 colored areas and nothing else. If a repaint contain more details then it look more real, and more beautiful. We do not have to go too far to check this point of view: you will not find any planes that is better detailed in repaints than our B747 and TU204. And if it depends on me, the list will grow time by time.
I think the commercial packages have only 1 advantage: the cockpit. A good virtual cockpit, and a nice panel (not a collection of many gauges, but really programmed together to be perfect) can raise the quality of a plane significantly. That is why I am too thinking of buying the B747 of PMDG when it comes out.
But at the moment I do not have any of the commercial planes so I could not test them in the game. That is why there are no EHM repaints for them.