Originally Posted by
UKtravelbear
11k miles is worth around £50-£60 quid off a future flight. So an upgrade would give you a lot more value for your miles.
So yes I think the upgrade route would be better value. Remember though that you'll also have some extra VS fees to pay as well as additional APD
The extra APD for "premium" certainly makes it harder to see the value in PE upgrades. More VS surcharges as well. I prefer simply paying for an extra legroom seat in Y.
11,000 miles isn't that far away from a one-way reward ticket, which depending on the route / dates, can still provide good value versus a cash fare. (the other one-way could be a cheap Norwegian flight or something) Of course the OP may have a much healthier mileage balance.