You can see in the pic above how close the feeder is to the reduced entrance on a nuc, and how far away it is below on a standard hive.
The biggest problem with a regular boardman is that if it leaks syrup, it will leak INTO the hive, and if your hive is tilted forward, it will build up in the feeder, kill bees, and eventually run along the reducer until it can find a way out, which is usually the entrance. There will be bees from Hawaii trying to get that syrup.
At the very least, if you MUST use an entrance feeder, drill a hole in the back of it. A small hole that will allow the syrup to drip there instead of running into your hive, making you bees sticky, and possibly killing them. Not to mention making the possibility of robbing even greater. The dripping hole in the back will still draw bees, but it will not draw them directly to the entrance, and it will also quickly alert you that there is a problem.