Without more information, holding the position that no AI could convince you let it out requires a huge amount of evidence comparable to the huge amount of possible AI’s, even if the space of possibility is then restricted by a text only interface. This logic reminds me of the discussion in logical positivism of how negative existential claims are not verifiable.
I have a feeling that if the loser of the AI Box experiment were forced to pay thousands of dollars, you would find yourself losing more often. Still it is interesting to consider whether this extra condition takes the experiment closer to what is supposed to be simulated or the opposite.
Consider Phlebas is subpar Culture and Player of Games is the perfect introductory book but still not full power Banks. Use of Weapons, Look to Windward, Inversions.. and Feersum Endjinn favourite non-Culture.
More to the point however, Look to Windward discusses part of the points you raise. I’m just going by memory here but one of the characters Cr. Ziller, a brilliant and famous non human composer, asks a Mind whether it could create symphonies as beautiful as it and how hard it would be. The Mind answers that yes, it could (and we get the impression that quite easily in fact) and goes on to argue how that does not take anything away from Ziller’s achievement. I dont remember the detail exactly but at one point there is an analogy with mountain climbing when you can just use a helicopter.
From my readings i dont get the impression that there is “competing on a level playing field with superintelligences” and in fact when Banks does bring Minds too far into the limelight things break down (Excession)