BD is actually a long super, it's downside being that using rb/r1 to move around faster drains it a lot. But it's also the only super that can recharge itself by getting kills. Technically, it's the longest lasting roaming super possible.

Bladedancer, sunbreaker and stormtance all have equal damage reduction of 50%. The only roaming super that doesn't get an equal armour boost is golden gun. Sunbreakers can last a long time but that's dependant on how many hammers they throw. If they spam, they can throw up to 7 hammers which can be over very quickly. Each hammer depletes a good chunk of super meter. If they conserve, they will throw less hammers but can make it last a while Stormtrance itself doesn't necessarily last any longer than bladedancer but it can with the right perk setup. There is a perk that grants a longer stormtrance if you have full melee and grenade charges. Many use this pretty effectively. Bladedancer can be short lived due to the way people use it also. Many spam attacks to close the gaps quickly which uses up a chunk of their super meter each time they attack. Ultimately all three can be used effectively in the right hands. And stormtrances grenades suck ass as far as I'm concerned which helps to balance the class somewhat.

Is that why when I am 1v1 stormcaller vs blad the blade kills me 90%of the time? The darting movements of the blade make it harder to shoot. If you use the perk that gives life on a hit it helps a ton too. It only lasts a shorter amount of time if you spam the attacks. Just like how blink on a stormcaller burns it faster.

I wouldn't say that blade dancer is easier to kill, simply that players have had a lot more time to develop instinctive strategies to defeat the subclass. For example: When you hear the hammer or storm activate you automatically begin planning what your next move will be. Either you will flee or you will use the most likely method to defeat the super. Usually a coordinated team can focus fire on the sunbro or the ticklefinger (stormtrance) and prevent a spree. In the case of blade dancing the best approach is taking your enemies by surprise or approaching from unexpected angles to prevent being shotgunned down. For stormtrance the range is such that there is a goldilocks zone. Too close, and a shotgun will end you. Too far and you're basically a sitting duck. Best to use wide corners to your advantage in that case. Sunbros are tough and if they have good aim or if your team is not well coordinated it would probably be better to just run and wait out the super. Blade dancer is extremely effective when used with blink when you plan your blink terminus to be right behind your enemy. By doing this you force your enemy to turn but by the time they do it will be too late even for a laggy player. People are just used to supers by now and that means coming up with new ways to use them. Experiment.

Because sunbreaker depends on the super. Bladedancer doesn't.

The other classes have an option to extend. Does blade dancer not have this?

Uhmm.... use encore and mask of the third man!?