I suspect you have already mentioned this in the past, and I possibly replied also in the past--this is something that I prefer also, having some extra space for carrying food. Last fall when I did a short two day trip and packed using less stuff, I was going to go with those new Arkel Dry-Lites panniers on my rear rack and a waterproof bag on top of the rack. I could have only gone this route, but it would have been tight, so I put the front rack on and used my old small front panniers and had lots of space for extra water in a 1.5 liter nalgene and food bought at the end of the day for supper, bkfast etc as I planned on camping where ever I stopped at the end of the evening along the trail.
Sure, adding the front rack and panniers added maybe 3 lbs, but I didnt have to scrunch everything into what I had on the rear and having the extra space for bulky food was nice.
Also, in this specific case I was on a rail trail with gravel for sections, so it was nice having the weight balanced out more (in the end, the second day was in heavy rain and the trail became so soft I bailed on it, partly due the amount of water and being on 28s)