Doing EWR - LHR on a 767-300, 2 seats. Any real difference between 21 F/D and 23 K/L, outside of the window/middle of course? Seatguru claims 21 F/D is a better seat and that 23 K/L have limited recline, but I've seen a couple of reports that 23 has the standard amount. I'd prefer the window, but if it's a less comfortable seat, I'd rather be able to sleep. Thanks!