Hard to say really. In FFR people aim to get AAAs/perfect scores on songs, BMS is more like Stepmania where you just have stuff that are impossible to score perfectly on. I think passing this might be comparable to AAAing a high FMO/low FGO (?), out of the 261 players that tried 52 can pass it based on internet rankings

So, compare this to FFR. What would this song be relative to FFR?