I have some beaconed layouts that the inserters are only one side of the belt, and have thought about this too. There have been times where the backed up lane backs up into the balancer at the beginning of the bus. I found this solution... If the belt balancer on the wiki reverses the side of the be...

I was curious to see when someone would create balancers taking advantage of the new underground lengths. Good to see that the search for better balancers isnt dead