You should also be aware that SQ KrisFlyer has similar earning restrictions on certain fares.

http://www.singaporeair.com/en_UK/pp...r_EliteSilver/

"Elite Miles" are used to track your progress towards *A tiers:
25000 Elite Miles are needed for KrisFlyer Elite Silver (*S)
50000 Elite Miles are needed for KrisFlyer Elite Gold (*G)

Again, seeing as you are on an Economy itinerary, I suggest you check your actual booking/fare class.

Economy: Y, B, E, H, L, M, W - 100% of actual miles flown
Discount Economy: N, Q - 50% of actual miles flown
Deep Discount Economy: K, V - 10% of actual miles flown

And should you decide to choose SQ KF as your FFP, and you are based in NZ, keep in mind almost all of NZ's cheaper Economy fares (such as Grab-a-Seat, many of the cheaper domestic fares, many Trans-Tasman/Short haul fares and a few Economy Saver long-haul fares) won't earn you anything towards SQ: http://www.singaporeair.com/pdf/ppsc...FOALLevels.pdf

Just some food for your thought.