I've not done much research other than reading the abstracts of studies into the various surfaces and trying to gauge what the opinion of the professional sport seems to be generally.
I think the studies speak for themselves - my interpretation is that there is a cause for concern. Specifically - that certain circumstances (which are common in contact sports) are far more dangerous on artificial turf than on grass.
Hence the significant increases in ACL and ankle injuries seen in many of the Gridiron studies - my initial guess would be that it's related to feet being planted/trapped and the person turning/twisting by his own actions or by the weight of a tackle.
Although it could be down to the hardness of the surface - which is probably also the reason behind the increase in muscle soreness (more energy having to be dissipated in the muscles, as opposed to through the mud).
I feel fairly confident that if you conducted a poll of everyone involved in premiership rugby (players, coaches, s&c teams etc.) you would see a fairly clear (strong!) preference for grass, and that they do think there is a tangible increase in the likelihood of injury on artificial surfaces.
Given the clear differences seen in the football/soccer studies, it makes sense that a study specific to rugby might be beneficial, however - the lack of surfaces actually being used by professional sides presents a bit of a challenge in obtaining the necessary amounts of data.