If you are taking 100% of the oil and putting it through a 20-40 micron filter that has an anti-drainback valve on it (most all do), then you aren't starving the bearings for oil (even at start-up), and you're removing all of the junk that the oil can't suspend - the same junk that eventually eats your bearings and cylinder walls in an unfiltered or bypass filtered system.
Don't discount the bypass system so easily. Not trying to force all the oil thru the filter at once allows for much, much finer media and all the oil will pass thru within a couple minutes. I use an Amsoil bypass filter that is 98% efficient at 2 microns and can guarantee my oil is far cleaner than any of Deve's schemes with no block modification.
Nearly all spin on filters have a disc and spring that will allow dirty oil to pass on by anytime in/out pressure differential exceeds spring pressure so for this reason I believe the full flow modification adds nothing more than a false sense of security.
