I'm in Project Radiation on Virtue with my primary. We are all Radiation primary defenders. In my experience, when more than 5 of us get together, we can take all purples all the time. With the stakced Rad Infections, we can stand our ground all day long with no worries... except some of the nastier toggle knockers that seem to hit no matter what.
Additionally, after level 28, those of us with rad secondary get blaster caliber firepower with cosmic burst. Some other secondaries also pack quite a punch, and with EF going, your basic blast power alone becomes an almost continuous stream of damage.
Another nice side effect of Rad teams, is that you don't really need to be the same level. Sidekicking works great because as long as you get rad infection and AM early (hahaha, I'm so funny), you can contribute easily. Just don't be the first to draw potential aggro if you are weak. Usually, when done right, the first round of aggro will only be sligtly effective because the first thing to drop on a group is infection. And everyone that's not initiating can just hit radiant aura when the first volley comes in.
One last observation is that level 12 and 22 are really power boosters for Rad teams. Those DO and then SO recharge reductions on AM reduce the critical mass to have multiple permanent AMs. Anyone that takes hasten can also set aside some AM slots for end recovery, although it's almost unneccessary. They only thing that drains your end with 5 AMs is a kamikaze power or a sapper (evil and accurate things that they are).
