Lucio can be played pretty much DPS style. As long as you’ve got heal on 99.9% of the time. Boost only when bringing people out of spawn and getting the hell away from ults. I like him because he’s good up where the action is to heal the most amount of people that he can but also can contribute to the damage. Lucio at close range is a bitch to deal with for the opposing team when played correctly. I try to majority play DPS while keeping at least 3-4 of my team mates in range at all times.
Side note: this doesn’t work great if your teammates are 5 solo goin’ buttheads. Overextending with a Lucio healer is just a crap idea. Gotta group up.