From personal experience Fire/Rad controllers aren't that good at soloing archvillains. They don't have any way to manage aggro like Ill/Rad can with Phantom Army and pretty much every archvillain worth a dime can take out a swam of Fire Imps with one AoE.
Terra is doable because she has boss-level magnitude, though you'll have to manage your toggles properly so you don't run out of endurance with RI, EF (and possible others like tactics) and throwing out char whenever it comes up. All she needs is one or two solid hits and you're going down. I didn't solo Terra, but I know I could have if I'd been more patient.
The only archvillains I've soloed are Anti-Matter and Neuron, but those fights were hardly fair considering I was L50 and they were L48. Even then Anti-Matter still got the best of me with a nuke not once but twice. Stupid heal-needing Imps.
Darke, just out of curiosity, was there room (endurance wise) for tactics in such a build? I'd think you could do without a few of those accuracy enhancements and instead slot for 3 damage on PA instead of 2 damage and 1 accuracy.
but being in Europe 8 PM - midnight EST is pretty much the middle of the night for me. So that's a no-go there. Would have been a perfect opportunity to try out Sonic Resonance as well, since I already have a mid-level FF and Kin on Virtue.