Its a bit of an odd one the desire for a 'full frame' camera. Until recently the larger sensor allowed a similar number of pixels to be made larger (still the case with the new D4/1Dx) so the image quality was better over a greater range of circumstances but now, as we are plunging down the path of huge pixel numbers, the difference isn't so great. The pixel density/size is identical on the D800 and D7000, the D800 simply has more of them due to it having a bigger sensor.
You also have to consider what is Full Frame? The 4/3 system is technically a full frame system as its not based on a 35mm one and the only lenses ever made for it have been designed specifically for that sized sensor. Its only our heritage of using 35mm as a base line that means we class it as a cropped sensor - its not. Its funny because when 35mm was released it was poo poo'd as being a miniature system and not the sort of thing that a 'real' photographer would use.