I was listening to the BIAB show, and appreciated the coverage of the subject. It was something that I considered for a while, before settling on a recirculating no sparge electric system that serves me very well.
There was one amendment I would like to make to the information given. The efficiency does not have to be anything like 65%, and I would not count that typical in my experience with no sparge brewing.
To get to the bottom of it, you have to follow your recent conversation with Kai Troester and break it into conversion and lauter efficiency. The limiting factor for BIAB and no sparge is the lauter efficiency. The lauter efficiency decreases as the total grain bill increases in a predictable way. This loss is due to absorption of water into the grain and deadloss in the system. To give real numbers for efficiencies from my system and its real losses, a 1.035 OG beer runs about 90%, a 1.050 beer runs about 87%, and to get down to 80% efficiency you have to get up to 1.076.
The second factor is conversion efficiency, and this is where I think no sparge gets a bad rap. If you are willing to pay attention to this number, then the numbers given above can be real. Through paying close attention to a fine crush, and malt conditioning to aid lautering at a fine crush (I constantly recirculate), I consistently get 97% conversion efficiency. With all of that pulled together, my last 1.052 American Amber came in at 83%.
I dont want this to become a dick comparison like so many efficiency arguments are, because I dont think that matters. I just would not want someone to avoid this way of brewing because it is always billed as incredibly inefficient. It does not have to be, and provides many benefits. Even with my two tank system and a 60 minute mash and 60 minute boil, I brew a normal batch in about 4 hours from water on to clean.
Joshua
out there who dick around with fly sparging, when all you need to do is pull a bag out and maybe, if you want to, rinse off the bag a little bit when you pull it out.