So once a Continuum had the Golden Ratio option 'implemented', it couldn't easily be reverted to the 'floorstanding style'?
No, not at all. The AD and 2.5 are different in this regard. The 2.5s are designed with the lower enclosure as a signle design. It uses this extension of the cabinet to allow for lower response.
The AD, which I have here, is basically a "stand mount" speaker and does not incorperate the lower module into the design and cannot be done at a later time.
They truly are different products.