Nearly everyone with F8x S55 engines on the forums use full SAPS like PP Euro 5W-40 (and did from factory, TPT 0W-40 was initial fill and maintenance oil) and definitely have less carbon buildup issues than N54 and somehow even N55 engines in the limited teardowns I have seen. I have seen no real evidence that anything but PCV system design is important here. Early VW DI engines and BMW N54 will have horrible buildup no matter what. I don't think you can get away from the fact that there is no port injection anyway and they will all require blasting at some point. BTW, the LL01FE has only recently looked mid-SAPS, the SN versions were classic full SAPS levels of detergents and ZDDP. The SP change was in 2022 so there have been many years of DI BMWs filled with full SAPS oils here.