Although the benefit I would find most useful if I travelled long-haul in Y would be the ability to ensure I got an exit row seat, which a silver card holder is pretty close to guaranteed if they want one, I would imagine. Even travelling short-haul in Y (which I do) I find this more valuable than the other benefits, except in the case of a significant delay when I find the lounge access the most useful thing - although there are other ways to get access to at least some sort of lounge.