For me weight distribution hardly matters, I adjust to any pack style after riding a minute or two. I can pack all my gear&supplies into two rear panniers, a small handlebar bag, and my tent strapped to the rack.
But actually I prefer four bags with everything packed including tent. I like the convenience of easily popping the panniers on and off the bike. I like having a separate kitchen bag for easy lunch breaks. The fours bags also allow extra room for fresh and/or bulky food items (a bag of bagels takes a lot of space). Having the extra space also lets me carry an extra day or two of food when heading into more remote areas.
For my tour this past July I only used small front bags. I had to pack a limited kitchen and keep food supplies to a minimum, so for me this is not optimal. The weight and distribution aren't really big factors for me. Anyhow here's my light packing (17 lbs base-gear) from this summer.