You're right. But how I think about it is: $0.80 SP minus $0.40...

You're right. But how I think about it is: $0.80 SP minus $0.40 cash backing leaves $0.40 enterprise value. Today's fall of ~6% reduced the enterprise value by ~11%. These falls are huge and can't continue much longer.

If the SP reached $0.60 the enterprise value would have halved from today... I can't see this happening. If it does though I will buy more. I have a buy order in now.

Osborne Copper and Gold is coming online in March and has projected steady state costs of $1.67/lb, right? Copper is US$3.15/lb, leaving a nice margin...

I'm happy enough for the SP to fall as long as the resource prices provide room to profit. I'll keep accumulating.