Oi! That pink foam was very realistic, I'll have you know! ;o)
As for stone rowing - I'm convinced it works. The terrain thing is just more proof that it could feasibly have been used as a method to move the stones.
The whole point, from my experience, is that the terrain is no obstacle - as much effort would be used regardless of how rough, bumpy, marshy, steep, etc the ground was...
Maybe not all the way from Preselli, perhaps, but over some of the lumpier bits of the route, it would cetainly have helped...
G x