Personally, I'm in 2 minds about POS vs POW.
I love the idea of getting rid of "wasting energy".
On the other hand, it's that "wasted" energy that gives the token additional undisputable value and is therefore a great layer of trust, next to the current trade prices on the exchanges.
Same effect as with gold. It's expensive to mine, hence it's rare, hence it's valuable. In theory, there should be some market-driven self adjustment happening to how much energy a coin consumes and I think that's what's happening. So POW isn't necessarily bad. Also, there are many voices warning against pure POS as there seem to be some issues with that, too.
I've thought about that topic a while ago, too and my feeling is that a new POW/hybrid POW/POS approach that somehow incentivizes contribution to coin network health might be a good approach. E.g. instead of just having the tokens "at stake", the POW part could be about providing network bandwidth (e.g. forwarding new transactions) or transaction history lookups. I'm not sure yet how to encapsulate these tasks in a way so that it can be verified independently that a node has done it. But it must be possible, SETI@home is somehow verifying processed packages as well.
The POS part could stay more or less the same as having tokens at stake I guess.
I agree with your comments on POW and POS.
Maybe POW is expensive in terms of energy, but it's what makes it work; and let's remember bitcoin is the biggest coin, the first and it still works pretty fine, regardless of all the attacks it got over the years.
Hybrid POW/POS could be a nice solution, but I'm not sure it's a good thing to introduce in a coin like XCN: I mean, what if those huge chinese xcn holders start staking? No coins for new users, no coins for small investors.
Furthermore, there is a technical problem to solve: miniblockchain is about removing transaction history and keeping a balance sheet of accounts instead, which clashes with the POS concept of "coin age"; since every node needs to verify the stake transactions, they would need to know the coin age and history of those coins. I'm not saying that it can't be done, just that we need to rethink it and adapt to mini-blockchain.
About SETI@home, they probably verify the packages in a centralised manner.
You know, that PoW, isn't so secure on alts in reality, because they have rather small processing power.
Stakers can secure coin, even if it's small, cause it's almost impossible to gather so large supply of coins in one hands.
And PoW always have limitation, as we can with Bitcoin - it's unsustainable, and it's getting absurd, when miners flew from one country to another, because they are forbidding them (for a good cause - tremendous energy waste is absurd, for sha256 algorythm, that don't contribute to humanity in anyway, nor it can be really used as a global super computer, because it's not designed so, and calculations of sha256, wouldn't have much usage).