Just a quick note - today I racked the Carob Porter beer from the primary fermenter into a secondary. It's been about 3 weeks. The beer was bitter but not spoiled, and was not sweet, so I'm hopeful the yeast got through all / most of the sugar.
There was a layer of material floating at the top, and of course a layer of muck at the bottom. I suspect the layer of top material is what would normally get blown off during fermentation - this was a half batch, the carboy is only half full, and in a full batch a good amount of material is carried out through the airlock during the fermentation. Because the top of the liquid was much further from the airlock, I suspect it is one reason it didn't happen this time (also the fermentation was not that vigorous). I managed to avoid most of the material (top and bottom) during the transfer, although some did make it over. Hopefully it will settle to the bottom during this stage.