For a flight at the end of November (LHR-SIN-BKK SK317) I have booked seats 81A & C.
71A/C are next to bassinet seats (72 DEGF) and I don't fancy the risk of a screaming baby next to me for 13 hours

.
After a little research I found four reported negatives for seats 81A/C H/K
1) It can get very cold
2) There is no window (but neither is there in 71 A/C H/K)
3) People may stand in front of you whilst they stretch their legs
4) Turbulance feels stronger at the rear of the aircraft
But being 6' 6'' the extra legroom is valuable and I was happy to pay a £120 premium for a return trip with Mrs Midnight.
I was seduced by SIA's June sale and this will be my first flight with Singapore after flying with Thai for 10 years.