I'm going to start off by saying I haven't tried any of these combos yet, but here are my thoughts on the primaries as a whole.
I'm pretty sure that (numerically) the only (de)buff set that is better on a corr than a defender is Storm, and that is primarily because Storm deals with extra damage nicely. The extra strength from the debuffs on a defender make Dark Miasma a very powerful contender. Between Darkest Night and Fearsome Stare you can get even level mobs on the to-hit floor. Throw in Dark Servant and you've got a lot to help with higher level enemies as well.
Although you can't ever "have too much defense debuffs" there is a limit in most of the game. the cap for to-hit is 95%, regardless of how much defense debuffs you have stacked or how much to-hit you have added to it, you always have a 5% chance to miss. The extra defense debuffs are still going to be nice on enemies that have some base defense. Rad also has Accelerate Metabolism (available very early) which will help your endurance recovery. Rad was probably the best (de)buffing set early in the game's history, but sets like Time and the change to buffs making ST buffs AoE make it a more even playing field. It's still a very strong set though.
Time is such a good set... I really agree with the concept of stacking the PBAoE Debuff with the seismic tremors (or whatever they're called). Time has the advantage over the other sets in that it has a very good self +defense skill, meaning it is easier to cap defenses.