LHR-LIN-CAT last week as FB Gold/Skyteam E+ with a second person on the PNR that doesn't have status:

We had to go to the Priority Check-In counter to add the status to the ticket and received:
- Extra Bags
- Fast Track in LHR
- Lounge Access in LHR (Plaza Premium) + Guest
- Priority Boarding both times
- Lounge Access in LIN (as it was a connecting international flight) + Guest

Everyone I interacted with was aware of the benefits to Skyteam status holders - overall a fairly painless process, apart from the fact that the FB number could not be added during OCI.