Correct me if I am wrong, but wouldn't this be just a platform or exchange site where all your bitcoins are in hands of that exchange? So indeed the transferring of bitcoin from one user to the other is fast because they would just be transferring funds over the platform and not over the blockchain. The blockchain is not easily changed, I believe you have to get 95% consensus to change it.
My guess is that you do off-chain transactions by swapping private keys in a cryptographically secure way. It can be done without a central server/exchange.
So this means that their concept is possible? But the bitcoin transfers would mean that it will not be on the blockchain. Which means that it would result to transactions secret or only be viewable in the exchange or platform where the transaction happened. I don't think I would support such as there are still dangers of the service stealing and running away with all the bitcoins.
