I don't see how BA gives preferential treatment to its own elites vs. OW Sapphire on BA flights. They all get priority check-in and boarding, seat selection rules are the same and mileage earning is exactly the same as AA Plat. Lounge access rules are also the same (at least for BA flights). I guess a Silver would get higher op-up priority, but that's about it. Am I correct to say that all OW Sapphires get the same treatment on a BA flight?

Background:
As someone who usually buys economy fares, the latest TATL changes have been huge for me and I'm seriously considering switching to OW. But before I compare the benefits to my current *G status, I need to decide whether I'd be using AAdvantage or BAEC. I'd be flying at least 2 longhaul trips per year on BA and I wonder if being a Silver would make the experience better compared to an AA Plat. Otherwise I'll have to decide based on other aspects of the programs.