I  like the two 30L barrels myself. If I am on a trip for 2 for a week, one 30L barrel will hold the food and the other holds all the other cook items...small pots/pans, stove, depth finder, gas etc... The two 30 L barrels together will hold enough food for 4-5 for 7-8 days or more depending on how much food you bring. I never tried the harnesses because I already had a pack that fit the two barrels. We always bring both barrels even though one would be enough just to even out the pack load.

I like to carry the 2 30L barrels in a pack so they sit side by side. It isn't uncomfortable to carry. Except for the weight the food pack/barrels are comfortable to carry. The only problem is it is easy to get that food pack too heavy. Another advantage of 2 barrels if by chance you have a bear encounter---hopefully you would discover the bear before he got both barrels. You are spreading out your risk so to speak.

Tim