I honestly haven't felt like my Corruptors, when solo, are doing that much more damage than my Defenders. So, yes, Scourge may kick in and be of use on bosses, and AV types of deals when solo, but if a Corr can get down to Scourge kicking in, then a Defender can get them down in health too.
Defender comes with some better Defense numbers too. I've enjoyed my Storm/Storm Defender more than my Storm/Storm Corruptor.
No, on Kinetics, I thought the Corruptor won out.