To me, this whole DOF debate is really simple. If one sets aside all the theorizing about why IMSBs fail and starts from the point where one has installed an unsealed ceramic replacement bearing, the DOF question boils down to these two questions:
- Does DOF substantially extend the operating lifetimes of unsealed ceramic replacement IMSBs compared to ones lubricated by being submerged in sump oil and splash oil?
- Does DOF create additional risks to engine and IMSB longevity and reliability?
No one that I know of has put a number on the table (or even an estimate for that matter) that answers the first question. If the answer to the first question is "no" or "not by much", then one doesn't need to know the answer to the second question because it wouldn't make sense to take the risk.