but where is the asset holders information stored, after the trades is cleared (transfer/payment).
The right answer is "in blockchain", obviously. That's the only way to make it secure and decentralized.
Think about it: if there was a way to store ownership information without blockchain, we would have cryptocurrencies other than Bitcoin.
There might be a way to secure transactions without proof-of-work, e.g. Ben Laurie's "mintettes":
http://www.links.org/files/distributed-currency.pdfBut since we already have PoW-secured Bitcoin, it just makes sense to use same PoW to secure asset transactions. Either via merged mining, or via embedding information right into Bitcoin blockchain.
I think that inventing and building a decentralized exchange with all the required parts is one of the coolest projects in the *coin world at the moment.
OT (OpenTransactions) guys have also done a massive amount of work and if those 2 projects/ideas can somehow be integrated... wow. Honestly, this stuff is exiting.
One thing that bothers me about the BTC type of blockchains is the ever growing size and it's vulnerability to 51% attacks. Also, lets not forget the huge cost (power) to keep it healthy and protected from all sorts of scumbags and losers with serious mental issues. BTC difficulty has soared to the level where small scale mining has become a pointless waste of time and looks like ASIC's will not help in this department. BTC mining will (has) become highly specialized business and this is probably not good at all. Concentration of power in to the hands of few greedy megalomaniacs and we go back to the "world" that BTC was built to avoid - money printing "fed" and it's greedy sock puppet "banks", who can remove you from the picture by a flip of a switch.
Sorry, I did not read the whole thread so it's a bit unclear how do the securities get issued. Second issue is "why keep mining". How is "mining" this stuff made financially attractive?