Of course you can win. Incendiary Grenade + sniper headshot + primary headshots + melee. In this order (you'll have to jump over him of course). It is easier to kill a sunbreaker than an arc blade who's lagging around and non stop teleporting (i do not use shotguns). Other than that ... Most of you are tacticians anyway (running away tactics ...) so you should have no problem with the sunbreaker.