Retinotopy (continued) 
If I am right, and only the spatial distribution of photoreceptors is significant, then the concept of Receptive Field will prove even more redundant, not to say misleading.
Right now this concept is centered on the spatial distribution of a group of neurons in relation to each other. If scrambling does not have any effect, then the sub-concepts of center and surround would lose any meaning they might still have, at least outside the retina.
Rerouting surgery like that performed by the Sur group gives me some hope that such an analysis could be one day tested empirically. (see my thread The Brain: some problematic concepts, the entry: "Where do sensations originate?" and further)

Also, a very simple explanation for the results obtained under the heading of receptive fields would be as follows:
Since there is no guarantee that we are dealing with a single photoreceptor (in fact, it is practically impossible), the On and Off responses could simply be the consequence of the light reaching the recorded cell or not.This does not explain all the results obtained, as "the absence or near absence of a response to simultaneous illumination of both regions, for example, with diffuse light".  On the other hand, such a lack of reaction is really remarkable. After all, it means that a whole group of neurons do not react to light. One wonders how we are able to look at a white patch without seeing spots immediately. Nothing in the concept or receptive field could explain such monochromatic images.