Hi Nate. Thank you for your response.
Regarding the risk of market manipulation and collusion on traditional order books, I agree that you don´t have those on Bancor. But these are theoretical risks because they might lead you or not to a wrong price. If you have a clear strategy / valuation of the asset you are trading, you will send your order at your desired price regardless of the machinations within the order book.
For smart tokens and relays it also exists a financial cost of staking the reserves. On top of that there is also the risk premium of that reserve being lost (stolen, accidentally frozen, etc). Not only the relay holders, but also the holders of smart tokens also bear the risk of the reserves being lost.
I believe it would be a good thing to carry out a detailed and quantified assesment of the financial costs and risk costs, the latter would theoretically decrease as smart contracts resilience (hopefully) improves over the years.