We need use smart contracts to improvement this IOU.
I'm not sure what smart contract functionality you're thinking we need. We could easily deliver OPEN.DAO directly to a user on BlockTrades as soon as his cryptocoin purchase was confirmed (so in about 10s or less if he buys the OPEN.DAO with BTS, or about 5 minutes if he buys with BTC). I can set it up tomorrow if you think that will bring in significantly more business for BitShares.
Edit: Oh, I just saw your post above. We don't really have time to change this, and I don't see why it should be such a big deal anyways. OpenLedger has already established it's reliability for making good on it's pre-sales with DGD. In case it's not clear what we're doing, we're buying the DAO up via the ICO, then offering an IOU for the quantities we've bought.