Back in the old days I played 5 scrappers to 50 (MA/Inv, Spines/Dark, Claws/Reg, Elec/Shield, Fire/WP) and I'm currently working on a Rad/Rad that's up to 33 and have just started slotting IO sets. Rad primary is good other than the activation time of a lot of the powers is pretty long. The cone is fidgety and hard to line up to get more than one - I can line up shadow maul with no problem but not this one. You don't get a good AoE until 32 (other than the aura). Rad secondary is very good, although you have to play it like Regen and avoid getting overwhelmed by too many mobs. The set has more +regen than straight heals, so you want to avoid letting your health drop too much. Beta decay is awesome, especially that the -DEF is autohit. You can laugh at shield generators and drones. Still debating whether to add Tough - will wait to see how it plays with the IO bonuses.