Indeed, the "Elite" membership has been around for a little while. Few clients are members and were invited to join via certain GMs at FS properties.
From a behind the scenes view...I have clients' Elite membership number then usually relate that to my FSPP Contacts/GMs when I make the booking for them.
Usually, a dedicated FS staff at the hotel will be assigned to look after the client and work with me to ensure all details/requests are carried through smoothly.

Can offer an extra level of care/attention and possibly better upgrade at times, but sometimes, it's also not really all that different than the normal FSPP booking/experience, in terms upgrades, other amenities...

If you have an Elite card, wonderful!!! If not, don't lose sleep over it