Cool example! But your argument relies on certain vagueness in the definitions of "satisficer" and "maximiser", that between:

• A: an agent "content when it reaches a certain level expected utility"; and
• B: "simply a maximiser with a bounded utility function"

(These definitions are from the OP).

Looking at the situation you presented: "A" would recognise the situation as having an expected utility as 9, and be content with it (until she loses the coin toss...). "B" would not distinguish between the utility of 9 and the utility of 10. Neither agent would see a need to self-modify.

Your argument treats Sally as (seeing itself) morphing from "A" before the coin toss to "B" after - this, IMO, invalidates your example.