[ford38v8]

This is another subject that has been discussed many times here on the Barn, with opinions all over the place. One fact that is not debated is the comparative effectiveness of the two different systems, particularly with the use of modern lubricants:
An original bypass system will filter 90% of your oil in a 15 minute drive, the time it takes to fully warm up your engine from a cold start.
A full flow system (or the easier 95% conversion which provides filtered oil to all but the rear main bearing), will never, I repeat NEVER, filter the finest of particles (I forget the micron value) that a bypass system provides.
In addition to that fact is the existence of a bypass valve within all spin-on filters, purposely designed to release (bypass) unfiltered oil when oil pressure rises too high within the filter.
A bypass filter system has no such excess pressure valve, and will simply slow the flow if the filter becomes clogged, which has no effect on oil delivery to bearings, because, of course, it is a bypass system.