Actually to me greeting is good but not necessary. Particularly if loading is heavy and they are very busy, some ISM / CP (KA) just rushed down the aisle and said "hello" then gone which I think is not necessary and I don't feel this meaningful as well.

The most meaningful greeting I had was my first flight with CX since I first qualify as DM (the fifth since DM, first four are all on KA). The ISM really had time to briefly talked with me and congratulate me to make DM (but nothing more...)

Back to the topic... If just comparing SL and GO, honestly I really can't think of any unpublished benefit difference... Maybe higher priority / faster answer in MPC hotline (5500)... But that's all