It has one extra perk beside a grenade... Sunsingers can spam solar nades to cut off an area for a good 15 seconds. More with Sunbreakers. I don't use this type of setup as I play Skirmish almost exclusively (the exception being Iron Banner and bounties) and use only Sunsinger. Sure, you can deal a lot more damage within a couple seconds as a Voidwalker than a Sunsinger could ever hope to do, but Sunsinger can do much more over a wider range and for a longer time. All you need to do is learn good applications for each Subclass as I already have, exploit their strengths, and get the kills you want/need.