My educated guesses:

Amex pays SPG ~1.4 cents per SPG point

SPG pays most airlines ~1.1 cents per mile,
(more than most CC companies pay their afflilated airlines. The CC companies get the lowest rates - only they have that kind of buying power)

Alliance carriers pay each other ~.7 cents per mile
(amount is likely based on a function of distance flown x class of service, not number of miles redeemed)

In the end, it is LX that provided stevens397's seat for rather little compensation.

This is a good deal for LX ONLY IF:
1) stevens397 would not have bought tickets on LX instead of using miles had miles not been an option.
2) The F cabin would not have sold out as paid tickets for far more compensation than LX gets for award tickets.