According to this interview/piece...'I asked an SRM engineer about the possibility of this and he tells me that it would be impossible for the osymetric chainrings to affect the readings of an SRM powermeter.'

http://www.cyclingtips.com.au/...-gimmick-or-miracle/

Thought it was a good article. Found the bit about Wiggins and co switching to round rings to train on a week before a race to get a 'turbo boost' then switching back the day before the start interesting.