I was told by a wise filter engineer at Filtran, "You can't have oil that's too clean."
Dave Newton makes compelling arguments that filtration below a "normal" threshold ( we'll call that around 94-95%@ 20um) does not result in "less wear" that can be measured on a macro level... with UOAs. That's likely true and I certainly have nothing to disprove his theory nor counter the evidence he presents. Still, I will go with the highest level of filtration I can buy within reason or budget. To me that means if I want to spend around $4 on a filter, I'll go for the P1 (99@20um) vs the MC (94%@20um)... all the usual caveats, yada, yada. You can extrapolate that to any OCI level or dollar budget.
Both he and I agree, and this has been proven on many levels, cleaner oil lasts longer in service because the additive package is depleted more slowly if the oil is kept clean. Maybe that means a 10K OCI vs a 7.5K and there may be the payback for the few extra bucks a premium filter costs. You have to use the extra capability to make it work for you, however.
As to location of the bypass, often touted as the major reason to go with the MC, more an more I see this as a non-issue because, as I was told repeatedly by several engineering types in the filter industry, bypass events are "uncommon" in the normal course of things. I've been watching my DP gauge setup for a few weeks now and have datalogged in several situations.. and the only time I have come remotely into the bypass area is on cold starts when I deliberately rev the engine pretty tight.... something I, and most of you, norally would not do. I got over 8psi DP only when I did a cold start, with oil temps in the mid 30F range and wound the engine up past 4000 rpm (5500 or so.. I hated doing it). The effect was magnified because I have 10W30 oil in the truck currently and the P1 filter has over 12K miles on it (less whizbang than it sounds because for 7K of that, I've had a bypass filter installed). It will be very interesting when I get 5W20 in it, with a new Ultra filter. In a perfect world,if I could get a full syn filter with efficiency at 99%@20um, or better, high capacity, premium features with a base end bypass for under $10.. I'd buy it. Alas...