Just thought that I'd update my earlier comments on this thread.
I harvested rye and spelt from my (small) Bonfils trial beds yesterday. I'll not know what the yields are like until the grain is dried, threshed, and weighed, but look a little low. In my system the grain beds are also the main providers of composting materials for the rest of the system. The addition of chicory to the understory has yielded masses of biomass, but may have reduced the grain yield.
As my rye is not a true Winter variety, I have the ability, by using modules/soil blocks, to harvest a crop before planting out the transplants.This will allow me to sow at the right time, but transplant later. I hope that this will either allow me to reduce the spacing between grain plants, or use adifferent interplant, either broad (fava) beans or an alternative grain.
I put a quick post about the harvest on my blog http://deanom.wordpress.com/2012/08/02/polyculture-update-and-small-scale-grain-harvested/
if any of you want to read about it.
My perennial rye and spelt is not yet ready to harvest.