Summoners are very good on high movement fights, that being over something like a black mage. I can have all my dots ticking on titan while I'm running from Bombs, Weight, Landslide etc. We do not have burst damage but you basically get 230~ DPS on a boss the entire time we are fighting it.

Part of the problem right now is also how people tank adds. For the most part a summoner would destroy if adds were all tanked on top of a boss ( Bane + ranging strikes DoTs = woah DPS ) + Shadow flare + Ifrit... thats a ton of damage.

On Titan we could do a lot of DPS to the Goal's if people were on his butt when they got 'rocked' since Bane would DoT spread to it. That rarely happens though so target switch means we basically point garuda at it with ruin spam since Bio wouldn't finish it's time.