Along the lines of what Johnny just wrote, if resawing with the band mill reveals more movement than would be expected from just moisture imbalance, the option to rip narrower is still there. I'd be more concerned about twist or bowing lengthwise in that respect and that can happen with narrow boards just as well as with wide boards. So I remain of the mind that I'd do the bandmill resaw first and then make plans from there since there is still a need to get it thinner anyway, regardless of other operations that may or may not become necessary depending on "the mood of the tree".
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The most expensive tool is the one you buy "cheaply" and often...