While not entirely certain: since the BBs for the 7800 and 7900 are interchangable, this would suggest that the ID bearing size is the same. Likewise since the 7900 crank fits the Madone, most likely the bearing width is the same. Now the seals are different, but that most probably is not referring to the Madone specific outer seal, but instead to Enduro's cartridge seal (enduro makes the cartridge bearings for Shimano).
This leads me to believe that the bearings are likewise interchangable.
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