Adam, I think your analysis is correct. I assume that Amsoil has designed the filter and restrictor correctly to get effective filtetration. My only beef is that the filters are expensive and the bypass filter will need to be changed frequently.
There has been a lot of discussion at www.tdiclub.com
around bypass filtration. I think the consensus there is that the toilet paper filters are the most cost effective approach. Some feel that on the small sump diesel engines changing the TP and topping off every 3,000 miles or so replenishes enough additives that you really never need to change the oil. Just change the full flow filter every now and again. Oil analysis will tell the tale.