Can't speak for their usage, but I calculated my token use with Copilot, my employer paid 22$ for >2000$ in tokens. Given estimates margins, Github is paying 98-99% of the costs for us. I imagine Claude max etc is similar. So it's not sustainable at all

No idea. Probably quite expensive. I usually run 4-5 concurrent CC sessions, so hard to pinpoint for just CHasm and Fe2O3