A week ago on IAD-LHR in biz, the (excellent) Purser taking meal orders said "Oh, I see you're a 1K. Welcome back! We appreciate your business."
While flying in F or BF I expect a greeting like that and have received it before. Though I expect the same greeting/treatment (at least relative to Y) if I were sitting in row 40 on the same flight, my guess is the latter happens far less.