I used boardman my first year with no trouble, but I was feeding 'all' the hives simultaneously which created, nor gave reason to rob. Top feeding is 'now' my go to choice 'flat out' and 'hands down'.... When I say top feeding, I mean the top has a hole cut in if for the feed jar to fit while the jars 'contents' and volume are visible in plain sight as when using a boardman, yet safe from entrance exposure to other bees....
Phillip