Assuming your dpm will go under the insulation and lap up under the sole plate there's not a lot of difference between the two is there? You'll just need to ensure the beams have the required bearing. Why is there an additional dpc beneath the beams?
Of course until the building is rendered, water will track along the beam in either case.
Looking end on at the beams, I found using concrete bricks with a generous bed of mortar filled the gaps between the block work below and the floor blocks. And fitted a few of the gaps with flat vent piope for ventilation of the sub-floor.
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