I used my Advance card to take advantage of Weekend First at the, er, weekend, and was on a refurb-ed 170 on the return leg (can't remember the number). The seat was noticeably less comfortable than the outward trip, and the arm rest had been replaced with a plastic one.
Still, I'd only paid for standard class, got a free cuppa and my advance card came as a result of an expenses-paid trip on the sleeper, so I can't really complain