Well, its not just a marketing, we are going to insure all the trades and use this as our competitive advantage, this is what we are planning to do.

We do store fiat, however the problem mainly focuses on bitcoins as they are simply too easy to be stolen, you just get access to the private keys and that is it, you are done.

The service you named is clever, however there are also some problems. Disputing issues using randomly selected artbiters is not much convenient in my opinion. These arbiters need to be involved in a heavywight process of verifying bank transfers (a.k.a reading the bank bills of others) etc. and it is quite risky in my opinion. Also sending money between bank accounts, as suggested, can take days, there is also a threat of possible bank chargebacks.

Another possible problem is with money laundering, as by definition there is a very little control. Solving this by some blacklists of dishonest nodes is not much effective, rarely these lists keep pace with the real world.

In case of BitStock I think there is one technical advantage as we do rely only on existing proved wallets like MultiBit, Bitcoin-QT, Armory, you name it. There is no need to reinvent the wheel by coding another node/client/bitcoin wallet using proprietary protocols.

BitStock exchange is running couple of months in production already. The concept has been proven and I think it takes best from both world bitcoin and fiat.

That being said, during early days of BitStock development I have been studying closely more of these concepts like Namecoin, Counterparty, NXT, Filestore, Ethereum and I have been impressed by each one of them, same goes with the bitsquare.io.