I could see them entrusting the rod bearings to the techs... the mains? Crank must come out, be treated properly/inspected. while doing so Have to hope it is installed correctly again tolerance wise and not damaging anything in the block (or the block itself) in the process... hope the bearing tolerances are correct... hope the motor doesn't end up like the M6 one Peter is rebuilding now...
Thats a lot of hope when asking R2M for a car... I get that they will fix it again if this breaks, but is that what you really want? Your car constantly in various states of disrepair over your ownership time?
No thanks... they should be doing factory engine swaps IMO if only to keep up the confidence - take these back as cores and supply a new crate motor like they do with DCT boxes and do the run around on changing the engine number for the owners at the licensing dept.
IMHO it WILL prove cheaper in the long run than letting techs change bearings (using limited knowledge, skill, experience or care... or perhaps all the above) and dealing with the aftermath