"Check-in faster than other passengers: regardless of the travel class booked, you can use the Business Class check-in counter."

Since catandmouse implies that this statement applies more widely (ie to more than LH), I guess I have to ask catandmouse why he thinks so.

Does catandmouse think that statement in a LH FTL brochure applies so widely that catandmouse can use business class check-in for any airline on the planet: British Airways, Delta, Qantas, TACA, Garuda . . . . ?

As to lounge access, the same brochure is quite clear (even if it is not so clear on business class check-in):

Lounge access

Relax before your departure in the exclusive Lufthansa Business Lounges, Lufthansa Frequent Traveller Lounges, Austrian Business Lounges, LOT Executive Lounges and Swiss Business Class Lounges.

For access to the lounges[*], you’ll need your Frequent Traveller card and a boarding pass valid for the same day and departure airport issued by Lufthansa, Lufthansa Regional, Adria Airways, Air Dolomiti, Air One, the Austrian Airlines Group, Croatia Airlines, LOT Polish Airlines, SWISS or another Lufthansa partner airline.

Nowhere does it say Star Alliance or TAP or . . . .