I searched out this thread because I wanted to see if anyone shared my The Prof as Digzone theory. You say assumed, as if you not longer think they are the same- Have you dropped that theory?
One thing that might go against this is that Diggers made square tunnels, while Reckoners made round ones.
I'm also thinking that his weakness would be related to the Diggers going mad- There was no real solid explanation for that. If it's a result of any human using a gifted power, I would have liked to have heard of the Enforcement teams going made from being gifted from Conflux. On the flip side, we already have a reason for the Prof not to use his powers (Retain his humanity), so that also being his weakness seems to be cheating. Perhaps it would be better if all gifted humans go slightly mad- Maybe that's the "Oh, you know" was in the Elevator, "Oh, you know, this signs of madness slowly destroying our Sanity"
Megan being an epic- I had her tagged as a possible one when the tensors didn't work for her, and I think the Elevator pretty much sealed it. I thought that was really well done- After having thought I had her "hidden reveal" already figured out, I stopped looking for one.
The one thing that didn't work for me was Night wielder still able to phase through walls when exposed to UV light.
I thought the Reckoners would have more Epics, honestly- I was looking for one to be the Tensor, one to be the Healer, and one to be the Jacket Forcefield, and the Prof's technology to be more along the likes of making any Epic a Gifter. I had Tia as the Healer.
I was also a Crossfire-style proponent- That he was only invulnerable if you wanted to hurt him. And I had Megan killing him- She pulled the trigger because she was a good soldier, but she honestly didn't want to. Which, perversely, would be exactly why her shot would kill him.