[Gelbster]

There is way more to this subject than the merely the specs of the bearing or discussing load vs lube.This is just conventional M96 wisdom.I am not an expert . 6204 & 5204 are just a dimension code. the Abec rating is a useful spec but C3 seems adequate.Tight clearances like 5+ may be a disadvantage ? then there is cage, seal, hybrids etc.
M96 engines may have different IMSB-related defects and to varying degrees. So are we discussing a better spec for a specific engine, a specific tye of bearing/year model or a panacea for all M96 ?
Let's exclude the collateral/ FOM damage failures because they are unrelated to IMSB specs.

Until you know the IMS-related defects(if any) in a specific engine ,how will you propose a solution for that engine ? And how does that spec apply to all M96 ?
For example -if Runout of the tube and/or sproket is the problem, tweaking ball bearing specs won't fix it. A plain bearing or a roller bearing might up to a limit . But what runout limit ?
If there are no IMS related defects in an engine , a1RS $3 OEM-spec bearing would probably be O.K. - particularly if the original bearing did not fail even after 100k miles. In such a case a superior spec bearing could be installed and after another 100k miles it would also be in good condition. Which would prove what about "better" bearing specs.?
Perhaps the best justification for using a "better" spec is that the upgrade costs little and does no harm - as long as you remove only 1 seal. 1RS seals do not seem to fail.Why?
The wisdom of using a plug in the IMS tube like "The Solution: has been reviewed and dismissed in previous discussions. For deep groove ball bearings and roller bearings 1RS works well in thousands of applications, so what additional benefits would the IMS Tube plug offer?
Note that seal failure often precedes IMSB failure. In which case, the primary cause of failure is seal spec/placement not bearing spec.
After years of participating in such discussions I have learned how much I/we do not know about this subject and just follow what works for people who install or warranty hundreds or even thousand of these bearings.Some of them still try to help in these Threads but it is futile.