In one of my trips this summer, I flew BusinessElite:

SFO -> ATL -> LGW and return via:
LGW -> CVG -> SFO

The inflight crew on all segments was pleasant as is the Delta norm, and I didn't notice any significant difference.

You should note that there is no BusinessElite lounge in CVG, just the standard CRC. Your international BE ticket entitles you to use both the CRC and BE lounges at ATL.

I frequently fly BE SFO <-> JFK, and was always told by the JFK CRC attendants that I can use the BE lounges and that they serve better snacks. The BE lounge seem to replenish the snacks fairly frequently, and I don't notice the feeding frenzie some FTers mentioned. YMMV