Hey Miguel, Thanks for the detailed comment.
First, let’s separate the risks of trading using a traditional order book, and the risks associated with staking funds in a smart contract.
With a traditional order book, you are matching two parties in order to process an order. It is assumed by the trader that these parties are unrelated, when in fact collusion and wash trades (i.e., trading between associated accounts to inflate demand) are rampant on traditional order books. In Bancor’s system, since there is no need for a counter-party, such manipulation attempts are far less effective because there is only one party involved with each trade.
As for the risks associated with staking funds in a smart contract to automate trading, these of course exist. Yet it’s important to first note that these risks only exist for buyers of the Relay Token (i.e., liquidity providers). Additionally, the owner of the smart contract is not Bancor but the Relay creator — a company/foundation/organization. If you don’t trust a group, don’t participate in their ICO and don’t donate to the liquidity of their Relay.
In terms of incentive structure, as you mention, one incentive for purchasing a Relay Token itself (as opposed to the tokens in its reserve) is to support the token project, community, organization etc. whose currency it may represent. Another mechanism which creates incentives is Relay creators can implement a fixed percentage of each trade to be deposited into the liquidity pool (thereby increasing its liquidity depth, all else held equal).
As for limit orders, this is definitely something on our radar and is getting prioritized accordingly. Developers could also built this functionality on top of Bancor if they want and we encourage them to do so.
Regarding your final point about tokens on Bancor Network charging a spread: a Relay creator can set the spread to always equal zero, or they can implement a fixed percentage on each trade to be deposited into the liquidity pool. While tokens are experimenting with various Relay models at this stage, the market design ensures the spread is fixed at every price level and fully transparent to traders.
