Jeremy Parish interviewed the producers of each game, learning interesting factoids about both. For example, Lancarse, part ofthe Etrian Odyssey development team, is responsible for Kage 2. And for the first time that we've seen, a Taito developer acknowledges the NES Demon Sword as a Kage series game -- before dismissing it. We had been wondering about that! And despite being a Taito side-view game with a lot of elevators (and, yes, some action), Exit was not inspired by Elevator Action.
Source - Kage 2
Source - Exit DS