At this point, how much real 'risk' would there be in a new digital currency? Far less than BTC.
I think this is a very interesting question. You're still left with the same problems though. Unless you can make the coin's real-life value constant in some way. Best I can come up with is increasing mining payout with the difficulty. That'll link the value of a coin to the cost of mining, directly. Meaning you can turn electricity into coin, but not the other way around. I suppose you'll need demurrage because else the coin will inflate beyond making mining cost neutral, and the mining rates will decline accordingly.
Actually.. Why isn't this how Bitcoin worked in the first place? Maybe it just complicates things too much.