This is a short and slightly crude comparison of 1080p 25fps output from the Canon XF100 and 720p 50fps output upscaled in Premiere Pro. I wanted to see if the 1080p footage (2,073,600 pixels) really resolved much more detail than the footage which is flagged as 720p (921,600 pixels).
In short, it seems not. An upscale plus a tiny amount of sharpening makes the footage indistinguishable (again, I stress this was a crude and basic test). The XF100 can shoot in 50fps at 720p…a huge advantage.